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LIBRARIAN. 





BLACKS AND PITCHES 


OIL & COLOUR CHEMISTRY MONOGRAPHS 
Edited by R. S. Morrell, M.A., Ph.D., FIC. 


UNIFORM WITH THIS VOLUME 


CELLULOSE ESTER VARNISHES 
By F. SPROXTON, B.Sc., F.L.C. (British Xylonite Company). 


IN PREPARATION 


THE CHEMISTRY OF DRYING OILS 
By R. S. MORRELL, M.A., Ph.D., F.L.C. (Messrs, 
Mander Bros.), and H.R. WOOD (Messrs. Storey, Smithson 
CS Co., Lids): 

THE CHEMISTRY AND MANUFACTURE OF 

PIGMENTS AND PAINTS 


2vols. By C. A. KLEIN, M.Sc. (Brimsdown Lead Com- 
pany), and W. G. ASTON (Messrs. W. Symonds & Co., 
Ltd.). 


THE PROBLEMS OF PAINT AND VARNISH 
FILMS | 
By H. H. MORGAN, Ph.D., B.Sc. (Messrs Naylor Bros., 
Slough). 
VOLATILE SOLVENTS AND THINNERS 

By NOEL HEATON, B.Sc. 


THE ANALYSIS OF PIGMENTS, PAINTS 


AND VARNISHES 
By J. J. FOX, O.B.E., F.LC., and T. H. BOWLES, 
Ene 


RESINS: NATURAL AND SYNTHETIC 


By T. HEDLEY BARRY and R. $. MORRELL, 
M.A., Ph.D., F.LC. 


OIL & COLOUR CHEMISTRY MONOGRAPHS 
Edited by R. S. Morrell, M.A., Ph.D., F.L.C. 


BLACKS & PITCHES 


BY 


H. M. LANGTON 
M.A. (Cantab.), B.Sc. (London), A.I.C. 
(Director, Messrs. J. B. Walker & Co., Ltd., Hull) 


NEW YORK 


D. VAN NOSTRAND COMPANY 
EIGHT WARREN STREET 


1925 








Richard Clay & Sons, Ltd., Printers, 





2 ‘ 
: ; 
we! 
‘ t 
y 
1 4 
a 


PREFACE 


In the following pages my endeavour has been to put before 
the reader a concise account of our present knowledge of the black 
pigments and of the various bituminous materials and pitches of 
commerce. Whilst it may appear at a glance somewhat strange 
to include in one and the same volume considerations of such 
apparently dissimilar and unrelated classes of substances as Blacks 
and Pitches, a little reflection will show the arrangement to be 
justified. ‘These two classes of substances are of substantial 
importance in a number of rather closely related Oil and Colour 
Industries. Moreover, in passing, it is interesting to record that 
the principal black pigment, carbon black, and the natural and 
petroleum residual asphalts are traceable to a common .origin— 
the petroleum fields. 

From those chapters dealing with the black pigments it has 
been thought preferable, for reasons which require no elaboration, 
to omit all but a mere reference to the blacks which originate in 
the synthetic dyestuffs industry. 

The task of writing on bituminous materials and pitches is 
rendered somewhat difficult by reason of the confusion still existing 
on questions of nomenclature and classification, but without 
entering fully into controversy, I have outlined a scheme of classi- 
fication, mainly based on that given in Abraham’s well-known 
treatise, ‘“ Asphalts and Allied Substances.” 

An effort has been made to indicate as concisely as possible the 
results of all the most important relevant investigations of recent 
years and at the same time to refer briefly to current theories. 
Though no claim to exhaustive treatment is made in the present case, 
it is my hope that nothing of material importance has been omitted. 
Suggestions are made as to the directions in which research may 
usefully be undertaken, and it is hoped that the volume will prove 
of service to many engaged in Oil, Colour, Paint, Varnish, Ink, 
Rubber, and Asphalt Industries. 

Every known source of information has been acknowledged in 
the text, but my thanks are due particularly to the Bureau of 
Mines, Geological Survey U.S. Department of the Interior, 
Washington, for the supply of several official publications and much 
statistical information, and for courteously permitting the repro- 
duction of much textual matter and a number of illustrations from 
Bulletin 192, on Carbon Black. My thanks also are due to the 
Statistical Department of the Board of Trade for the supply of 
data, to Mr. C. Ainsworth Mitchell for kindly loaning the blocks 


Vv 


ae eee 


v1 Preface 


relative to Figs. 1 to 4, to Mr. A. R. Warnes for his kindness in 
granting permission for the reproduction of Figs. 16 to 19, to 
Messrs. Bennett, Sons & Shears, Limited, for the loan of the block 
for Fig. 20, and to the British Engineering Standards Association 
for authority to include several of their well-known British Standard 
specifications. 

To the publishers my thanks are extended for useful advice and 
counsel and. for the care taken in the preparation of the text and 
in the reproduction of the illustrations, whilst I am particularly 
indebted to the editor for much useful assistance and criticism whilst 
the book was in manuscript. My friend Mr. R. J. Whitaker has 
kindly read through some of the chapters dealing with carbon 
black. 

Thanks are also tendered to my wife for much valuable assist- 
ance in the tedious work of compiling tables and in the preparation 
of the index. 

For any inevitable errors of omission or commission the author 
alone is responsible. 

H. M. Laneton. 

July, 1925. 


CONTENTS 


2 PAGH 
PREFACE : ; . ‘ ‘ ; ; : ; ; Vv 


CHAPTER I 
INTRODUCTION ; : : ; ; : : ; fe 38 


System of Classification—General Occurrence and Methods of Prepara- 
tion of Black Pigments. 


CHAPTER II 
GRAPHITE ' 4 : ; ‘ : : : ‘ ; 16 


Occurrence in Nature—Manufactured Graphite—General Properties and 
Uses in Manufacture of Lead Pencils and Graphite Paints. 


CHAPTER III 


THE Fixep CARBON BLACKS . j ; : ; : 22 


Bone Blacks, Wood Charcoals and Mineral Blacks—Mode of Preparation 
—Properties. 


CHAPTER IV 
Carbon BLAckK ‘ : | Z : ere 3 


Its Manufacture from the Natural Gas of Petroleum Fields—Statistics— 
Theory of its Formation—Commercial Methods of Manufacture by the 
Channel Process, Rotating Disc Process, Plate Process, Roller Process 
and by Thermal Decomposition—Attempts at Alternative Methods of 
Production—General Properties and Analyses—Methods of Testing— 
Uses of the Pigment. 


CHAPTER V 


LAMPBLACK  . : , , ’ ee 
Methods of Production—Properties, Uses and Analyses. 


CHAPTER VI 
Buack PIGMENTS IN Paint MANUFACTURE : : é ees 


Consideration of the Physical Properties Involved—Various Uses of 
Black Pigment Paints—British Standard Specification for Carbon Black. 


CHAPTER VII 


Brack PigMENTS FoR INK MANUFACTURE : : ; ; 55 


Different Classes of Work requiring Printing Ink—Properties of Blacks— 
Long and Short Blacks—Chemical, Physical and Practical Tests on 
Printing Ink Blacks—Some Photomicrographs of Ink Pigments. 


CHAPTER VIII 
CARBON BLACK AS A RuBBER PIGMENT . ; ; : me 


Factors concerned in the Use of Compounding Ingredients in Rubber— 
Tests for Carbon Black in Rubber—Change in Elastic Constants— 
Stress-Strain Relationships. 


vii 


Vili Contents 


CHAPTER IX 
PircHES AND Bituminous MATERIALS. : ‘ ; , 
Introduction—Factors Involved in Classification—Definitions—Complete 
Classification. 
CHAPTER X 
THE CHEMISTRY OF THE BITUMENS AND PITCHES . ; 


Paraffinoid, Aromatic and Naphthenic Hydrocarbons—Nitrogenous, 
Oxygenated and Sulphur Compounds, 


CHAPTER XI 
MetTuops oF TESTING Bituminous MATERIALS AND PITcHuEs 


American and British Standardisation—Physical, Heat, Solubility and 
Chemical Tests and their Uses. 


CHAPTER XII 
NATIVE ASPHALTS 


Origin and Relationship to other Naturally Occurring Bituminous Bodies 
—The Bermudez and Trinidad Pitch Lakes—Composition of Natural 
Asphalts. 


CHAPTER XIII 
ASPHALTITES . 5 : : ; : E : ; 


Gilsonite, Manjak and Grahamite—Their Occurrence and Characteristics 
—The Asphaltic Pyrobitumens—Elaterite, Wurtzilite, Albertite, Imp- 
sonite. 


CHAPTER XIV 
PETROLEUM ASPHALTS, OR RESIDUAL PITCHES . ‘ ; 


Occurrence, World’s Production, and Refining of Petroloum—Charac- 
teristics of Residual, Blown and Sulphurised Petroleum Asphalts. 


CHAPTER XV 
CoAL-TAR PitcH AND ALLIED PITCHES . : ; : hig 


Residuals in Pyrogenous Distillation—Occurrence, Genesis and Com- 
position of Coal—Destructive Distillation of Coal—Composition, Pro- 
perties and Uses of Coal Tar—Coke Oven, Producer Gas and Blast 
Furnace Tars—Distillation and Properties of the Resultant Tar Pitches. 


PAGE 


75 


83 


91 


98 


105 


112 


Contents 


CHAPTER XVI 
MISCELLANEOUS PITCHEs . : ‘ : 


Wood-tar Pitch fromy Hard and Soft Woods—Wood Distillation— 
Rosin Pitch—Peat and its Distillation Products—Peat-tar and Lignite- 
tar Pitches—Water—Gas and Oil—Gas-Tar Pitches and their Properties. 


CHAPTER XVII 
Fatry Acip Pircues : ; : ‘ 


Subdivided into Stearine Pitch, Cotton Seed Pitch and Wool Pitch— 
Saponification of Fatty Oils—Cotton Black Grease and Wool Grease— 
Distillation Plant and its Operation—Characteristics of Various Stearine, 
Cotton and Wool Pitches—Bone Tar Pitch. 


. CHAPTER XVIII 

Tue WEATHERING AND AGEING OF BiTruMINoUS MATERIALS 
Effects of Exposure to Air, Sunlight and Moisture—The Light Sensitive- 
ness of Asphalt. 


CHAPTER XIX 
BirumMINous Faprics ; 


Roofing Felt—Floorings and Floor Coverings—Bituminous Cements, 
Insulating Coverings and Papers—Waterproofing and Damp Coursing— 
Manufacture and Uses of Bituminous Fabrics. 


CHAPTER XX 
Bituminous Paints, VARNISHES, ENAMELS AND JAPANS 


Nature of Bituminous Bases Used—Volatile Solvents to be Used— 
Bituminous Paints and Varnishes Protective against Rusting and 
Exposure to Chemical Agents—The Jellying of Asphalt Paints—Japans 
and their Uses—Pitting of Japans. 


CHAPTER XXI 
Bituminous PAvinec MATERIALS 


Roadway and Pavement Construction—Surface Phenomena in con- 
nection with Asphalt Pavement Construction—The British Standard 
Specification for Tar and Pitch for Road Purposes. 


APPENDIx I. 
AprenpDIx II. 
APPENDIX III . 
INDEX OF NAMES . ‘ : : : : 


INDEX OF SUBJECTS 


129 


138 


142 


151 


164 


171 
173 
174 
175 
176 


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MARK MADE BY BORROWDALE GRAPHITE . . facing page 19 
MARKS MADE BY FABER’S PENCIL. : as 19 
MARKS MADE By ACHESON GRAPHITE PENCIL 2 19 
Line In Drawine oF 1831 = 19 
SELLING PRICE OF CARBON BLACK . : . 7, page: 28 


CHANNEL PLANT IN COURSE OF CONSTRUCTION . facing page 31 


METHOD OF CONVEYING CARBON BLACK .~ . . page 32 
CARBON BLACK PLANT IN DETAILED PLAN ; . page 34 
DEPOSITING SURFACE FOR CARBON IN THE RotTatTInG-DIsc 
PROCESS ; : : : : ; . facing page 34 
DETAILS OF THE PLATE OR CABOT PROCESS : = 34 
THE ROLLER OR ROTATING CYLINDER SYSTEM . . page 36 
ARRANGEMENT OF A LAMPBLACK PLANT . ; . page 43 
PHOTOMICROGRAPH SHOWING AGGLOMERATED PARTICLES OF 
SHORT CARBON BLACK . : : : . facing page 59 
PHOTOMICROGRAPH SHOWING DISPERSED PARTICLES OF LONG 
CARBON BLACK . i : ; ; . facing page 59 
PHOTOMICROGRAPH SHOWING AGGLOMERATED PARTICLES OF 
LAMPBLACK : : : : : . facing page 60 
Pian oF Hirp’s Contrnvous DIsTILLATION PLANT . page I17 
Hirp’s ContTINUOUS COAL-TAR DISTILLATION PLANT . wage 118 
Hirp’s ContINvous CoAL-TAR DISTILLATION PLANT . page 120 


Hirp’s Continuous CoAL-TAR DISTILLATION PLANT . ; 
facing page 120 


Fatty Acitp DISTILLATION PLANT . ; : = 132 


XX. 
XXII. 
XXII. 
XXIII. 


XXIV. 
XXYV. 
XXVI. 
XXVIII. 
XXVIII. 
XXIX., 
XXX, 


LIST OF TABLES 


PRODUCTION OF GRAPHITE 
ANALYSES OF GRAPHITES : : : ; 
COMPOSITION OF PIGMENTS IN ContTh’s PENCILS 


YIELD OF CHARCOAL FROM AIR-DRIED Woop 


RESULTS OF ANALYSES OF VARIOUS CHARCOALS 
CARBON BLACK PRODUCED FROM NATURAL GAS 


CARBON CONTENT AND QUANTITY OF CARBON BLACK 
RECOVERED FROM NATURAL GAS . 


ANALYSES OF CARBON BLACKS 


ANALYSES OF CARBON BLACKS, LAMPBLACKS AND 
OTHER BLAcKs (SELVIG) 


ANALYSES OF CARBON BLACKS 
ANALYSES OF LAMPBLACKS AND OTHER BLACKS 


BuLKING VALUE AND Ol ABSORPTION OF SOME 
PIGMENTS . ? ; : : : ; ; 


PROPERTIES OF BLACKS . 
CARBON BLACK AS A FILLER FOR RUBBER 


Tuer RESULTS FOR MIXINGS CONTAINING 20 VOLUMES 
oF PIGMENTS 


OrIGIN, PuysicAL PROPERTIES, SOLUBILITY AND 
CHEMICAL COMPOSITION IN CLASSIFICATION OF 
PITCHES AND Brruminous MATERIALS . 


TyprEs oF BITUMINOUS SUBSTANCES AND PITCHES 


COMPLETE CLASSIFICATION OF BITUMINOUS SUBSTANCES 
AND PITCHES 


TESTS TO BE APPLIED TO BITUMINOUS SUBSTANCES 
MaRrcusson’s SUBDIVISION OF ASPHALTS . ; 
CoMPARISON OF SOME PETROLEUM DERIVATIVES 
WoRrLp’s PRODUCTION OF PETROLEUM 


PRINCIPAL REFINERY PRODUCTS FROM CRUDE 
PETROLEUM i 


RESIDUALS IN PyroGENovuS DISTILLATION 
COMMERCIAL DISTILLATES FROM GAS WorKS TAR . 
CHARACTERISTICS OF Various Tar PitTcHES 
DISTILLATION PRODUCTS FROM PEAT 

COMPARISON OF SOME RESIDUAL PITCHES : : 
WaTER-GAS T'ARS : : - 

ANALYSES OF Woon GREASES : 


xi 


63 


68 
69 


72 
84 
96 
98 
106 


107 
113 
115 
119 
125 
127 
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BLACKS AND PITCHES 


CHAPTER I 
INTRODUCTION 


System of Classification—General Occurrence and Methods of Preparation 
of Black Pigments. 


THE black pigments of commerce find use in the manufacture of 
black paints and varnishes, in black printing inks, in stove polishes, 
as compounding ingredients in manufactured rubber and in a 
variety of other ways. With one or two exceptions, all the black 
_ pigments contain carbon in one or other of its numerous forms as 
their essential colouring principle, carbon being an ideal pigment 
on account of its stability. It is unaffected by exposure to light or 
air, is resistant to acids, alkalies and other chemical agents, and 
suffers neither dissolution nor discoloration in contact with them 
or in admixture with alcohols, oils, etc. It is destroyed only at — 
high temperature when combustion ensues. Being usually in the 
amorphous state, and finely divided at that, carbon pigments can 
be readily compounded with the usual paint and ink vehicles, giving 
extensive tinting and covering power, though these pigments vary 
considerably amongst themselves in shade and strength and in 
covering power. The carbon pigments can be mixed with other 
pigments and the usual vehicles without causing any alteration in 
them or being themselves altered, and as paints made from these 
pigments are slow in drying, such paints require more than the 
usual amount of driers. 

A rational system of classification of the black pigments is some- 
what difficult and the best is one, due to Cruickshank Smith,! which 
takes into consideration both origin and method of production (see 
page 14). 

In this scheme of classification the term “‘ fixed ”’ is applied by 
Cruickshank Smith to those carbon blacks in which the pigment is 
“fixed ’” by an incipient coking process applied to suitable raw 
_ materials, which are carbonised in a combustion chamber to which 
a restricted access of air is permitted, and the pigment as produced 
is retained within the combustion chamber. 

It will be noted from the following list that a variety of blacks 
containing elementary carbon exists, and unfortunately there is a 
lack of precision sometimes in describing them; particularly is 
this the case with carbon black and lampblack, it being often 
quite erroneously assumed that these are alternative names for 


14 Blacks and Pitches 


one and the same substance. Actually the various carbons and 
charcoals have different physical and chemical properties, they 
are varied in their physical structure and the uses to which they 
can be put. They are not identical in chemical composition nor 
are they pure carbon. 


Black oe 


Carbonaceous ) Metallic 
| ee bias 
Coloured by Compound Black Oxide Black Oxide 
elementary (Lakes, inks of Iron of Manganese 


carbon and dyes) (Fe,0,) (MnQ,) 
Soe | 


fl 





__fNatural Graphite Fixed Carbon Deposited Carbon 


| Artificial we Blacks or Soot Blacks 
| 


DOD) 9s 


Vegetable Black 
Mineral ,, 


Carbon or Gas 
Black, ete. 





Ivory Black 
= at Kes Black 


Blue Re 
Charcoal Black 
(various) 


The deposited carbon blacks are made by one or other of the 
following methods, according to Roy. O. Neal ?: 


1. Formation by direct contact of a flame upon a depositin 
surface. eee 

2. Production by combustion of an oil, tar, etc., in an inadequate 
supply of air, where soot is allowed to settle slowly on the floors 
and walls of the collecting chambers. 

3. Carbonisation of solids and subsequent reduction to a state 
of small subdivision. 

4. Production by heating carbonaceous vapours or gases to a 
decomposition temperature by external heating with or without 
air in the forming chamber. This method is usually referred to 
as cracking or thermal decomposition, and so far is only in the 
experimental stage. . 


Method 1 is that in use in manufacturing the typical carbon 
black of the American trade, whilst method 2 gives rise to the 
familiar lampblack whose first preparation and use are lost in the 
depths of antiquity. The carbonisation method, of course, leads 
to the production of all the familiar charcoals. 


Introduction 15 


Graphite, in addition to being of natural occurrence, is also to a 
certain extent artificially prepared in the electric furnace. 

The compound carbonaceous blacks, the lakes and dyes, of which 
the nigrosines may be cited as typical examples, have their genesis 
in the synthetic dyestuff industry. 

As regards the metallic blacks, their interest, so far as they enter 
into the manufacture of inks and paints, is now mainly historical. 

Black oxide of iron, Fe,O, (or FeO-Fe,0,), occurs in nature as 
magnetite in many parts of the world. When pure it is an iron-black 
substance used occasionally in some cheaper black paints and, in 
admixture with other blacks, in certain cheaper qualities of printing 
ink. 

Black oxide of manganese occurs as pyrolusite (MnO,) in Czecho- 
Slovakia, Spain, France and parts of N. America, in very pure 
iron-black or steel-grey, rectangular, rhombic prisms, though often 
as fibrous masses. Seldom is it, though, that it is found in the pure 
condition—more often in association with other manganese ores. 
When ground and finely powdered it is occasionally used as a pig- 
ment under the name of “‘ manganese black.”’ 


REFERENCES. 


1 “ The Manufacture of Paint.’’ Scott, Greenwood and Son, 3rd edition; 
1924. * “‘Carbon Black,” Bulletin 192, U.S. Dept. of the Interior, Bureau 
of Mines, 1922. 


CHAPTER II 
GRAPHITE 


Occurrence in Nature—Manufactured Graphite—General Properties and 
Uses in Manufacture of Lead Pencils and Graphite Paints. 


GRAPHITE, known also as plumbago and blacklead, is a form of 
carbon which occurs as a mineral widely distributed throughout 
the world, generally in compact crystalline masses, but sometimes 
in foliaceous, scaly masses and even sometimes in a fibrous form, 
the variations being somewhat dependent on the locality. The 
production for the past few years is given in the following table * :— 


TABLE I. 
Production of Graphite (Metric tons). 





1921. 
LFOPIOGINT 5, sake pasa mp oiaptee dae beks 30,000 
AIMTGOC) ECAWOR non l san cse ues eeeera 2,346 
CRTISGE LU Aiisibs natu teeaee 367 
DEBBI ay sslec tor ak ok ae 3,088 
Austria and Styria .........seeeee 10,800 
Bohemia and Méahren ............ 8,500 
BUT e ean cack ad oer sone aebitaat ee 3,000 
COG ROE. 2 oss nnin ota Ca Teen ate Guananie 4,422 
SPDR sip boixansiecuas vais meee er ee 950 
REIIIOOM as. os cacao ket Vikas ao ealera deieeies 11,000 
DEAGAGEROAN ois lies vatenscadaenhnee — 
Other COUNETICS ........cc0cesccccees —- 

TL Ota St kictk ts ccaesore te oeeerbest 85,000 100,000 136,498 


In England, graphite was found at Borrowdale in Cumberland 
as far back as 1560, but the supply is practically exhausted there.* 
The best qualities are now found in Ceylon, whereas the poorer 
qualities occur in Sweden and Bavaria, the ash in specimens from 
these sources being sometimes 40—60%. In the U.S. the quan- 
tities are often insufficient to make it worth while to work them in 
some localities. 

Graphite is velvety-black or steel-grey in colour with metallic 
lustre, is opaque, quite soft to the touch, and makes a grey mark 
on paper. It crystallises in small hexagonal plates, though it also 
occurs amorphous, and it is then sometimes difficult to distinguish 
sharply between graphite and the usual amorphous charcoal forms 
of carbon. The specific gravity varies from 2-25 to 2-35 when pure. 
The principal impurities with which it is found in association are 


ferric oxide, alumina, silica and lime, the carbon being present to 
16 


Graphite hy 


the extent of 75—92%. For purification it is crushed and levigated 
and subsequently the ash content reduced by chemical treatment. 

A certain amount of graphite is now manufactured by the 
International Acheson Graphite Company at Niagara Falls, U.S.A., 
the amount having been about 3700 tons in 1920. This manu- 
facture is due to an observation by E. G. Acheson that carborundum 
at a temperature above 2000° C. is decomposed into carbon and 
silicon, the former being in the form of crystalline graphite. He 
subsequently observed that coke could be converted into graphite 
in the presence of much less silica than would be required to convert 
the whole of the carbon into silicon carbide, and he therefore con- 
cluded that the action was catalytic. It is now known that all 
forms of carbon can be converted into graphite under suitable 
conditions of temperature, though the rate at which this occurs 
varies greatly with conditions and with the nature of the reactants. 

At present graphite is manufactured by the Acheson Company, 
according to H. D. K. Drew,°® by the following U.S. Patents: 
542,982 of 1895; 568,323 of 1896; 617,979 of 1899: 645,285 of 
1900; 702,758 of 1902, and 711,103 of 1903. For graphite powder 
a furnace similar to that favoured in carborundum manufacture is 
adopted. : 

Carborundum is used in constructing the furnace walls, the 
end-walls through which the electrodes pass being fixed and the others 
movable. The furnaces, which may be 30 ft. in length and of 
sectional area 18 ins. by 14 ins., contain a charge of clean anthracite 
in fine powder containing up to 10% ash, packed round a core of 
graphitised coke. Petroleum coke is used for making the best 
qualities of graphite. A current of 3000 amperes at 220 volts is 
first passed, but later, as the resistance decreases, the final current 
is 9000 amperes at 80 volts, the duration of the operation being 
about 24 hours, after which the graphite is cooled, removed, and 
ground in tube mills, and by air separation the fine material sifted 
from coarse particles. 

Manufactured graphite in addition to containing 1—2% of 
amorphous carbon may contain up to 10% of ash, though in the 
case of the purest form the ash is no more than 0-:2%. 

A method for the rapid analysis of graphite has been described 
by G. B. Taylor and W. A. Selvig,® but space forbids a description 
here. 

Uses. 

Natural graphite is mainly used for the manufacture of plumbago 

oe 75% of the total supply being absorbed in this way; ’ 


18 Blacks and Pitches’ 


the remainder is accounted for by lubricants 10%, pencils 7%, 
foundry work 5%, paints 3%. Artificial graphite finds its use for 
electrodes, lubricants, paints, dry batteries and in boiler-scale 
preventives. 

Its uses in the manufacture of crucibles, electrodes and foundry 
work are outside the scope of the present volume, though brief 
reference may be made to its use as a lubricant. Flaked graphite 
can be used dry in steam cylinders, and it is said to build up a 
surface on rough bearings; it is sometimes compounded with 
compound greases for heavy bearings and with lubricating oils for 
light bearings. Its lubricating properties in colloidal suspension 
have been discussed by H. L. Doyle * and a method of deflocculating ' 
graphite has been patented by E. G. Acheson.® The fact that 
colloidal graphite is, however, very susceptible to the flocculating 
action of electrolytes, less than 0-1°% of free fatty acids being sufficient 
to precipitate it, would appear almost to inhibit its use in this way. 

It is well to remember in mentioning the lubricating pro- 
perties of graphite that both it and the diamond are crystalline 
forms of the element carbon: the former soft and greasy to the 
touch, the latter one of the hardest substances known and in 
powdered form strongly abrasive, in striking contrast to the lubri- 
cating character of its graphitic allotrope. The new method of 
X-ray analysis has given the clue to these striking differences in the. 
two allotropes, differences which must be accounted for by differences 
of molecular structure. 

A full account of graphite as a lubricant is given in a memoran- 
dum on Solid Lubricants in the Report of the Lubricants Com- 
mittee,/° to which the reader is referred for full information. 

Graphite has no great use as an oil or varnish colour except in 
the manufacture of anti-corrosive paint for use on ironwork, and 
according to Zerr, Riibencamp and Mayer !! is used exclusively in 
many parts of Europe for blackleading iron stoves, its fire-proof 
properties rendering it very suitable, and in the painting of sheet 
iron as a preventive against rust. The manufactured graphite 
when finely ground is similarly used as a paint. According to 
H. A. Gardner,!” graphite gives a better paint coating when mixed 
with other pigments, such as red lead and sublimed blue lead. He 
points out the great tendency in graphite towards agglomeration 
of particles. In addition to being proof against rusting, graphite 
in a paint imparts immunity against the corrosive action of gaseous 
sulphur compounds, ammonia, the halogens and their gaseous 
derivatives, etc. 


A 





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PHOTO-MICROGRAPHS OF PENCIL MARKINGS 





Fig. 1.—Mark made by Borrowdale Fic. 2.—Marks made by Faber’s 


Graphite used for Pencil-making in Pencil. Striations show sequence of 
1851. Now in Geological Museum. lines. x~20. 
x 20. 





Fia. 3.—Marks made by Acheson Fic. 4.—Line in Drawing of 1831. 
Graphite Pencil. Striations show Typical of old pencil markings. 
sequence of lines. xX 20. x 20. 


Graphite 19 


The most important use to which graphite is put with which 
we are concerned here is in the manufacture of black-lead pencils. 
According to Ainsworth Mitchell,* the graphite of Borrowdale was 
used from the time of its discovery, about the year 1560, until the 
latter half of the nineteenth century for the manufacture of the pencils 
used throughout Europe. An account of the properties and uses 
of graphite in this connection is given by Cesalpinus,!* though 
apparently the true nature of graphite was not known until 
demonstrated by Scheele in 1779. 

About 1840, when the Borrowdale mine was becoming exhausted, 
efforts were made to utilise the accumulations of graphite dust, 
and a patent was taken out by Brockedon,“ according to which 
finely-sifted graphite was induced under great pressure into the 
form of compact blocks which could be sawn up in the usual way. 
About the middle of the last century, however, the composite 
pencil was coming into use, having first originated with Conté, of 
Paris, in 1795. 

In Conté’s process finely elutriated clay and graphite are mixed 
to a paste forced through dies in a cylinder, and the circular threads 
of pigment dried, heated in a covered crucible and afterwards 
fixed into the grooved wooden holders with which we are familiar. 
Since that time such developments as the incorporation of wax, 
lampblack, resin, etc., with the pigment have arisen. 

According to Mitchell,* the suitability of graphite for pencil- 
making depends, from a chemical aspect, on: (1) the proportion 
of carbon, (2) the amount of silicates, (3) the iron. Moreover, 
the physical nature of the carbon in the graphite appears to be 
of importance, and this is borne out by microscopical examination 
of marks produced on paper by graphite. In the microscopical 
examination, both vertical and horizontal lines are recommended 
by this author to be examined, using a 1 in. objective and with a 
strong side light. Under these conditions, in the case of Borrowdale 
graphite, the vertical lines show relatively few straight striations, 
and when these occur in the heavier strokes they are disjointed 
and irregular. 

Table IL gives the results of some analyses of graphite due 
to Mitchell,* by whose courtesy also it is possible to reproduce the 
photomicrographs he prepared. 

For an account of the method of analysing pencil pigments the 
reader must consult the original paper. 

Marks made by pure graphite, when examined under the micro- 
scope in a vertical position with illumination at right angles, show 


Blacks and Pitches 


20 


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Graphite 21 


irregular silvery strokes or broken striations. In the modern pencil 
pigments, in which clay is incorporated with the graphite, fine 
beaded striations parallel and uniform throughout the pencil mark 
appear. An examination of Figs. 1, 2, 3 and 4 enables these 
differences to be appreciated. 

Mitchell * has also given the composition of a number of pencil 
pigments made by the Conté firm, reproduced below : 


TABLE III. 


Composition of Pigments in Conté’s Pencils. Series 1020. 


3 Loss at 
ae Graphiti 200-210° C. Iron oxide 
a aan Silicates. | with traces Remarks. 
& ‘ Wax, of Al,O3. 
a etc. Ash. 
% % Yo % % 
0 60-28 12-85 26-87 23-70 2:07 Puce-coloured ash 
1 55:43 17:71 26-86 16-54 5-93 2 
2 57:63 13-76 28-61 25-61 1-90 © 
3 50-80 10-60 38-60 34:95 0-28 “a 
4 48-52 12-21 39-27 34:98 3-79 a 
5 36°06 8-4] 55-53 36-29 5-35 Titanium present 
REFERENCES. 


3 J. Soc. Chem. Ind., 1922, 44,246r. 4 C. Ainsworth Mitchell, ibed., 1919, 
38, 3837. °® Martin, “‘ Industrial Chemistry,” Vol. IT., 1918, Section LXXXVI, 
- 404. &® Bulletin 112, U.S. Bureau of Mines, 1920, 43. 7 J. Soc. Chem. Ind, 
1920, 356r. °® Journ. Phys. Chem., 1913,17, 390. °% U.S. Patent 1,223,350 of 
1917. 4° ‘‘ Report of the Lubricants and Lubrication Inquiry Committee,”’ 
Dept. of Scientific and Industrial Research Advisory Council, H.M. Stationery 
Office, 1920. 11 ‘‘Colour Manufacture,’’ Charles Griffin, London, 1908. 
12 “Paint Technology and Tests,’ 1911. 3% “De Metallicis,’’ Libri Tres, 
Paris 1602, Cap. VII, 186. 44 English Patent 9977 of 1843. 


Bibluography—Graphite. 

Electro-Chem. and Met. Ind., 1902, 1, 52; 1905, 3, 253; 1907, 5, 452. 
Met. and Chem. Eng., 1911, 9, 536; 1913, 11, 242. Trans. Amer. Electro- 
chem. Soc., 1902, 1, 53; 1902, 2, 43; 1907, 12, 29; 1911, 20, 105. A. J. 
Allmand, ‘“‘ The Principles of Applied Electro-Chemistry,’’ London, 1912. 
J. Wright, “ Electric Furnaces and their Industrial Applications,’’ London, 
1910. ‘‘ Graphite, its Occurrence and Uses,”’ Bulletin Imp. Inst., London, 
1906, 4, 353. H.S. Spence, ‘“‘ Graphite,” Dept. of Mines, Ottawa, Publica- 
tion No. 511, 1920. J. G. Bearn, “ The Chemistry of Paints, Pigments and 
Varnishes,”’ Ernest Benn, 1923. Thorpe, ‘‘ Dictionary of Applied Chemistry,” 
1921-1924. J. W. Mellor, ‘“‘ Inorganic and Theoretical Chemistry,” Vol. V., 
Longmans & Co., 1924. F. Cirkel, ‘‘ Graphite, its Properties, Occurrence, 
Refining and Uses,’’ Ottawa, 1907. 


CHAPTER III 
THE FIXED CARBON BLACKS 


Bone Blacks, Wood Charcoals and Mineral Blacks—Mode of Preparation— 
Properties. 


THE basis on which the blacks, described in this chapter, are differen- 
tiated from other black pigments has been mentioned along with 
their general method of preparation in the introductory chapter. 
Leaving out of consideration the mineral blacks, the “ fixed ’’ carbon 
blacks are known perhaps more familiarly as the charcoal blacks, 
and they all have the same genesis. When non-volatile carbon- 
aceous substances are heated in closed retorts or kilns out of contact 
with air, such substances undergo decomposition, and water, certain 
volatile carbon compounds, such as carbon dioxide, carbon monoxide, 
acetic acid, acetone, hydrocarbons, and certain oily, tarry or resinous 
compounds result, and a residue of elementary carbon, associated 
with a greater or lesser amount of mineral ash, remains behind in 
the retort. The amount and nature of such elementary carbon or 
charcoal remaining depend on the nature of the raw material, the 
type of plant used, the temperature at which the operation is carried 
out and the extent to which volatile decomposition products are 
removed from the sphere of action. This method of producing 
charcoal blacks is termed dry distillation. 

A convenient subdivision or classification of the black pigments 
to be reviewed here is the following : 


(a) Bone Blacks, including ivory black and drop black. 

(6) Wood Charcoals, including vegetable charcoals and vine 
black. 

(c) Mineral Blacks. 


This subdivision serves to indicate the origin of the black, and 
to some extent is further justified by some of the characteristics 
exhibited by these various blacks. 

(a) Bone Blacks.—These are made by calcining bones in air- 
tight retorts, the bones being previously freed from adhering fat 
and ground to a coarse powder and sifted. During calcination, 
when black for pigment is the primary need, the products of com- 
bustion are burned instead of being recovered, the claim being that 
a better product results, but this is purely conjectural. At any 
rate, the bone black so prepared has greater colour-strength and 
better working qualities than sugar-house black, where, during the 
calcination, the by-products of the dry distillation are suitably 


recovered, and the black is obtained in a granular form. After 
22 


The Fixed Carbon Blacks 23 


being used in sugar filtering, it is washed, ground wet, dried and 
afterwards finds use as a paint pigment under the name of Drop 
Black. 

If bone black be treated with acid and the calcium salts dissolved, / 
a finely-grained carbon almost free from ash results. Acid-washed 
black has a very deep black colour, and in consequence of its fine 
state of division a great deal of colour-strength. 

Ivory black is a form of bone black made, not, as formerly, by 
charring the waste cuttings of ivory, but by the dry distillation of 
the best quality of bones obtainable after defatting, etc. Ivory black 
is more intense in blackness than the average quality of bone black. 

A very important use for bone black is as a decolorising agent 
and deodorant in the filtering of sugar and other solutions and oils; 
although it is outside the scope of the present volume to discuss the 
utility of bone black in this direction, reference may be made to 
the recent work of P. M. Horton and W. D. Horne,!* on the 
réle played by bone black (or animal charcoal, as it is sometimes 
termed) in decolorising. It is interesting to note, however, 
according to Oliver Wilkins,’ that much of the bone black used 
as a pigment comes second-hand to the colour manufacturer from 
the sugar refiner. The “spent” animal charcoal of the latter is 
thoroughly washed and ground by. heavy stones to reduce the 
spongy, carbonaceous matter to a fine, silky powder. According 
to this author, the old custom was to sell this black in lumps made 
by dropping the black paste, as it came from the levigating stones, 
in little heaps on to boards for drying, and the following out of this 
prescribed ritual and the production of the black in peculiarly 
shaped pieces was a criterion of purity. To some extent even 
to-day this procedure has to be adopted in order to satisfy those 
users who are unconvinced of the purity of finely-ground bone black 
sold in the form of a powder. 

Generally speaking, the various bone blacks are denser than 
carbon and lampblacks. They are of bluish-black colour, have a 
specific gravity of 2-6 to 2-80 usually, and are characterised by a 
high content of ash, often as high as 80% or upwards, with a corre- 
spondingly low carbon content, which may be as low as 10%, the 
ash being largely calcium phosphate. 

(6) Wood Charcoals.—The old-fashioned method was to carbonise 
wood in heaps, taking care that access of air was very restricted, 
but the method had many disadvantages, and owing to lack of 
proper control of air supply, temperature, etc., it was impossible 
to manufacture a product of uniform composition and of guaranteed 


24. Blacks and Pitches 


purity. Ultimately, therefore, the method of heating in retorts 
or air-tight crucibles was resorted to, as in the manufacture of bone 
black. 

The subject has been reviewed by T. W. Pritchard,1® who refers 
to the old destructive distillation process carried on in a series of 
retorts fitted with condensers set in brickwork, under which was a 
furnace. Temperature control is an important feature of the 
operation. This process gave a high yield of products. 

Later, the process of subjecting to steam distillation wood rich 
in resins and turpentine was resorted to before commencing 
carbonisation. 

A modern process, followed in the United States, and termed the 
solvent process, is to take pine wood, which is shredded and then 
extracted by means of solvent naphtha, which removes in good yield 
the turpentine and resins, which are recovered after removal of the 
solvent. Subsequently the extracted wood is carbonised. 

The yield of charcoal from wood depends, of course, on the 
nature of the wood carbonised and on the way it is heated. G. 
Martin ® has given some statistics illustrative in this connection of 
the yield of charcoal from air-dried wood, viz. :— 


TasueE IV. 
Yield of Charcoal from Air-dried Wood. 


Nature of wood. Charcoal yield %. 
Beech slowly heated .........cseeceaes 26:7 ) 
“f QUICHE Eh oe icc nteh cy eee “21-9 
Oak slowly heated ..........ccsee0e 34:7 
= WIGHT. 30. cudotadetes eens 27-7 
Birch slowly heated ..........cccesees 29-2 
¥ Cg neta eee 21-5 
Pine slowly heated ......,....ccce00 30:3 | 
2 QUICKIES vo cai5 ccd eeas abe eereneee 24-2 


Besides the resinous woods, such materials as sawdust, coconut 
shells, cork cuttings, beech twigs and leaves and similar vegetable - 
matter are carbonised, particularly for the production of vegetable 
charcoal, though for the true vine black, now largely of historic 
interest, vine twigs, grape husks and washed wine lees are carbonised. 

The apparent specific gravity of the various charcoal blacks 
varies from 0-106 to 0-206, but when air-free they have a real specific 
gravity of about 1:8. With the exception of vine black, none of 
them has any great colour-strength, though they are used mixed 
with other black pigments. 


The Fixed Carbon Blacks 25 


In the table given below are the results of analyses of a number 
of bone, wood and other charcoals examined in the author’s labor- 
atory 1*« during the past four years. 


TABLE V. 


Results of Analyses of Various Charcoals. 


Volatile Fixed 


Material. Moisture. Ash. mietbae. east. 
> (a) Oo oO oO 
O oO Oo Oo 

Boome black 2. cicescscccsesss vee Oe Ae id ba 
A SS | Se 3°35 78-52 8°86 9-27 
Vegetable charcoal I ...... 3°70 3°35 6-70 86-25 

a rs 17 ee Sees 6°57 3:40 6°78 83°25 

2 ae) 6s oe 6:49 4-42 10-71 78°38 

ie ato od" Sate naee 5-30 4-50 9-28 80-92 
Willow charcoal ............ 3-26 2:10 13-66 80-98 


With the exception of the bone blacks, none of the above was of 
intense black colour. The bone blacks were high in ash content and 
their texture was not so fine as that of the other blacks recorded 
above. Some of the vegetable charcoals were particularly fine, 
having almost the fluffy texture of a typical American carbon 
black. 

(c) Mineral Black.—This is a black pigment made by grinding 
a black form of slate or clay shale which has a carbon content of 
about 30%. This shale exists widely distributed, occurring in a 
specially pure state in Spain, less so in Switzerland, the Tyrol and 
Italy, and is generally blue-black to brownish-black in tint. 

Certain so-called mineral blacks are also produced, similar to 
the above in character, by carbonising in retorts waste coal dust and 
Scotch boghead mineral, the charred mass containing up to 30—40% 
of carbon. 

According to Gardner,!* mineral black, owing to its low carbon 
content, has only a low tinting power, though it finds use as an inert 
pigment in compounded paints. It has a flocculent appearance, 
the particles showing a strong tendency to mass. 


REFERENCES. 


15 P, M. Horton, J. Ind. Eng. Chem., 1923, 15, 519. 18 W. D. Horne, 
ibid., 1922, 14, 1134. 17 “The Manufacture and Properties of Pigments 
for Paints,’? Oil and Colour Trades Journal, April 25th, 1924, p. 1165. 
18 “ Recent Developments in Wood Distillation,” J. Soc. Chem. Ind., 1912, 
418. 1918, p. 325. 18 Unpublished results. 


26 Blacks and Pitches 


Bibliography—Bone, Charcoal, and Mineral Blacks. 


B. E. R. and J. A. R. Newlands, J. Soc. Chem. Ind., 1888, 7, 419. T. L 
Patterson, 2id., 1903, 22, 608. C. H. Hall, J. Ind. Hng. Chem., 
1922, 14, 18. G. Barfi, German Patent 168,034 of 1904. F. E. Bartell and 
E. J. Miller, J. Amer. Chem. Soc., 1922, 44, 1866; 1923, 45, 1106. J.C. 
Lawrence, J. Soc. Chem. Ind., 1918, 87, 7. H. K. Benson and L. L. Davis, 
J. Ind. Eng. Chem., 1917, 9,!141. Thorpe, “‘ Dictionary of Applied Chemistry,” 
1921-1924. ‘“‘The Utilisation of Wood Waste by Distillation,” Harper, 
St. Louis, 1908. ‘Production of Bone Black.” W. Jones, U.S. Patent 
1518072 of 1924. 


CHAPTER IV 
CARBON BLACK 


Its Manufacture from the Natural Gas of Petroleum Fields—Statistics— 
Theory of its Formation—Commercial Methods of Manufacture by the 
Channel Process, Rotating Dise Process, Plate Process, Roller Process 
and by Thermal Decomposition—Attempts at Alternative Methods of 
Production—General Properties and Analyses—Methods of Testing— 
Uses of the Pigment. 

CaRBON black is the fluffy, velvety-black pigment produced in the 

form of an impalpable powder by the burning of natural gas against 

a metal surface. This black is not to be confused with lampblack, 

from which it differs in several respects, and which is made by 

entirely different methods. According to G. L. Cabot,!® who is 
one of the pioneers of the American carbon black industry, certain 
printing-ink makers of New York and Philadelphia found that the 

soot, deposited by the suitable burning of artificial gas, gave a 

beautiful gloss and an intense tint to printer’s ink, differing in both 

these respects from the older and more familiar lampblack. 

The first recorded use of natural gas for lighting purposes in 
the U.S.A. occurred as far back as 1826 in New York State, but it 
was only in 1872 that its general use for domestic purposes came 
about, the gas being conveyed along pipes from the gas wells of the 
petroleum fields. The same year saw the erection at New Cumberland 
of the first factory to manufacture carbon black on a commercial 
scale.2 In this factory gas from a gas-holder passed through 
pipes to gas-jets arranged in the same horizontal plane beneath 
slabs of soapstone that were pierced with numerous orifices, through 
which excess smoke and waste gases passed. Over the slabs was a 
roof provided with dampers for controlling ventilation. Transverse 
horizontal scrapers below the slabs were supported, and moved 
in horizontal grooves in the lower and opposite sides of the roof, 
the scrapers from time to time removing the carbon black deposited 
by the burning of the gas. The carbon black fell into sheet-iron 
troughs suitably supported. The depositing surface was kept 
cool by an arrangement dependent on continuously circulating 
water. 

The first lot of 500 lbs. of carbon black marketed sold for $2.50 
per lb., but by 1881 the price had fallen considerably, and 
the movement in the selling price since then is indicated by the 
chart 2 (Fig. 5). Whereas the total production in 1881 was pro- 
bably only 400,000 to 500,000 lbs., by 1920 it had risen to about 
50,000,000 lbs. 

Since the early establishment of the carbon black industry 

27 


28 Blacks and Pitches 


numerous innovations have been introduced and considerable 
advances made in the methods of manufacture. The extent and 


60 


50 


ee 





Pa 
es 
Pe 
pee 














Cents per Found. 
bo 
s} 














® 


yeahs 
Fic. 5.—Selling Price of Carbon Black. 


value of the industry are best gathered from the following table, 
due to E. G. Sievers 7°: 


TaBLe VI. 
Carbon Black Produced from Natural Gas. 


Average 
N Quantity Average vine teq Quantity of 
meted produced Value $. aa black per; gas used 
(Ibs.) icon 1000 e. 





———— | |) | | 





1919 
West Virginia ... 23 | 29,925,614} 2,358,119 79 | 1:3 23,117,332 
Louisiana ......... 7 | 14,024,606 933,334 6-7 | 0-7 20,291,021 
Wyoming ......... ; : 
a. ee 2 4,868,947 231,747 4-8 | 1-1 4,306,153 
Oklahoma. ...... : , 
Ranhisles) 2 2,922,274 244,726 8-4 | 1:5 1,954,029 
Pennsylvania ... 2 315,500 48,114} 15-3 | 1-4 227,700 
36 | 52,056,941} 3,816,040 7:3 | 1:04 | 49,896,235 
1920 
West Virginia ... 19 | 26,659,469] 2,221,674 8-3 | 1-43 | 18,628,780 
Louisiana ......... 15 | 18,565,498! 1,455,764 78 | 1:0 18,099,800 
Wyoming ......... ] 
Montana ......... 1 5,850,313 326,424 5-6 | 1:6 3,673,108 
Kentucky ...... ie ue 
Pennsylvania ... 2 246,612 28,424 | 11:5 | 1-2 197,290 


eS) — SS | — | | 


39 | 51,321,892| 4,032,286 7-9 | 1-26 | 40,598,978 


Carbon Black 29 


The variation in the average yield of carbon black per 1000 c. ft. 
of gas burned is indicated in these figures. It must be remembered 
that there are considerable variations in the price of gas in the 
different fields. The industry is necessarily a migratory one— 
gas may become prohibitive in price in a particular district or 
the supply may become intermittent or fail altogether. 

In selecting the location of a plant, an idea of the ultimate supply 
of gas available should be obtained by reference to rock pressure, 
thickness of gas-bearing strata, porosity of the sands, the presence 
or absence of intruding waters, and some knowledge of the previous 
_ history of the field and of the drilling which has been practised. 
The following summary, due to R. O. Neal,?! is useful in this 
connection : 


“When planning the construction of a carbon-black plant, 
information on the following points should be obtained; distance 
from railroad or navigable stream, depth of wells, thickness of gas- 
bearing strata, gas pressure, gasoline content and knowledge as to 
whether gas is casing-head or dry, amount of proven territory, 
history of field, drilling practice, location of field in regard to large 
centres for domestic and industrial distribution of gas, distance 
from large trunk pipe-lines for transportation of gas, open flow 
capacity of gas wells on prospective leases, and a test on the richness 
of gas for the approximate quantity of carbon black that one expects 
to procure per thousand cubic feet.” 


It is important to test natural gas for its carbon-black value 
both by chemical analysis and by means of special test apparatus in 
which a known quantity of the gas is burned and the carbon black 
deposited on a metal plate, collected and weighed.”* 28 The varia- 
tion in the amount of carbon black obtained from different qualities 
of gas burned by the same process is given in Table VII, due to 
D. B. Dow.? 

It will be observed that the yield of carbon black from natural 
gases follows very closely the ethane content, the heating value 
of the gas and its content of elementary carbon calculated from the 
hydrocarbons as determined by analysis. Methane (CH,) contains 
33:5 lbs. of carbon per 1000 c. ft., as against a content for ethane 
(C,H,) of 67 lbs. per 1000 c. ft., and the bearing of this is seen in 
the yield of carbon black obtained in the case of Wyoming natural 
gas. 


Theory of Formation of Carbon Black. 


The burning of natural gas in an incomplete supply of air results | 
in the liberation of carbon, and the combustion, contends Bone,?4 


30 Blacks and Pitches ‘ 


TABLE VII. 


Carbon Content and Quantity of Carbon Black Recovered from 
Natural Gas. 


Louisiana. Virginia. Wyoming. 
A. B. C. D. 
MRL GHG «i sassis cele ean obs per cent. 94:12 70:75 | 65-23 46-45 
PTOI. Gass bcescrasentane sce ri 3:44 24:14 | 30-07 43-10 
Carbon dioxide ............ * 0-50 0:28 1-56 0:96 
NWatnOROn ©) c12. Weg naecticnees 1-94 4-83 3°14 9-49 


Net heating value in B.Th. U. ’ per 

c. ft. at 0° C. and 760 mm. pres- 

BOTS 5. < Cd saunas: cas Ow eense in lbs. 962 1,086 | 1,134 1,176 | 
Carbon per 1000 ec. ft. of gas cal- 

culated from carbon content of 


methane and ethane .... in lbs. 33:8 39-9 42-3 44-3 
Carbon black per 1000 c. ft. of gas 

reported obtained ......... in lbs. 0-80 1-00 1-10 1-40 
Percentage reCOVery — ..ccseseseceess 2-4 2°5 2-6 ol 


takes place according to the following scheme as a result of hydroxyla- 
tion : 


B Sra via C 
Oxidation H,:C:(OH), i 
‘ a ° e 
CH yg (ACOH! 5 
g 8 8 
@|& Pac 2 | 
OM Olan Oo | 7 
ali al =| 7 
& 8 8 
AY ay A | 
C + 2H, CO + 2H, co + H, 
A’ B’ i 


The tendency is always to pass from A to C. When the pro- 
portion of methane to oxygen is that which is expressed by CH, + Og, 
the reaction passes from A to BtoCtoC’. Iftheratiois 2CH, + O, 
or higher even, then only a part of the methane can be oxidised 
through the reaction A to C, and so part is decomposed at A by the 
heat evolved in the A to C reaction. The minimum amount of 
oxygen in which a methane flame will burn is 15-6%. Only in the 
inner part of the flame, where oxygen supply is low but where the 
heat is sufficient to decompose the methane, will carbon be evolved, 
and the percentage of carbon to be obtained by the incomplete com- 
bustion of methane is low; gases rich in ethane and its higher 
homologues give higher yields of carbon. Bone noted that the 
decomposition of methane, in the explosive combustion of hydro- 
carbons, was a surface effect leading to a hard, gritty carbon, whilst 








Fia. 6.—Channel Plant in course of Construction. 


Carbon Black at 


the decomposition of ethane, ethylene, etc., took place throughout 
the whole mass of the gas and yielded a soft carbon. The decom- 
position of methane and the influence of different surfaces on this 
have been discussed by W. E. Slater.?5 

The function of the cold metallic surface, which is a feature 
of all the commercial processes for making carbon black, is to cool 
the liberated carbon in the flame sufficiently to prevent its com- 
bustion, but obviously an optimum temperature is necessary. 
Too cold a surface may prevent the maximum separation of carbon— 
too hot a surface will cause too much carbon to be burnt and may 
even change the physical characters of the carbon remaining. In 
this connection a carefully regulated air supply is possibly the chief 
desideratum, whilst the best temperature is about 500° C. 


Commercial Methods of M anufacture. 


The principal methods in commercial practice in U.S.A. are the 
following, arranged according to the quantity of black produced : 


1. Channel process. 

2. Small rotating disc process invented by A. R. Blood in 
1888 and now extensively used. 

3. The large plate process invented by G. L. Cabot. 

4, The roller process invented by E. R. Blood. 

5. Thermal decomposition or cracking. (This is still largely 
in the experimental stage.) 


The Channel Process.—Briefly this is operated as follows, accord- 
ing to R. O. Neal, who has described the process in detail in the 
Bulletin.” | 

The natural gas from the wells, after suitable pressure regulation, 
passes through gasometers, which regulate the flow of gas, and pass 
it on to burners arranged in the condensing buildings. It is essential 
that equal gas distribution be obtained in each building. The con- 
densing buildings are of sheet iron, about 700 ft. long and 8 to 10 ft. 
in width, arranged in rows along both sides of an alley, through the 
centre of which alley and placed at right angles to the condenser 
units is the main driving shaft operating the machinery within the 
units. 

In the interior of the buildings are trestles or tables about 6 ft. 
wide and about 6 ft. high, and on each trestle are usually placed 
8 rows of channels, these latter being hung from trucks that run on 
overhead rails. The channels have a reciprocating motion of 4 to 
5 ft. \ 


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Carbon Black 33 


In Fig. 6 (A and B), taken from Bulletin 192 of the Bureau of 
Mines, U.S. Department of the Interior, Washington, and reproduced 
here by the courtesy of that Department, particulars of a channel 
plant in course of construction are shown. 

The gas is burned through lava tip burners, there being usually 
1600 of such in a building of the size described here. An even, 
luminous, smoky flame results, the draught being suitably regulated, 
and the carbon black is deposited on the underside of each channel. 
Underneath the channels are arranged the carbon-collecting hoppers, 
spaced about 4 ft. apart, and these catch the carbon removed by 
scrapers set in the hoppers; different types of scrapers with different 
methods of actuating them are in use, but one type in use is that 
shown in Fig. 7, reproduced from Bulletin 192. 

The carbon black is conveyed by spiral conveyors to a room 
containing bolting machines; these are galvanised sheet-iron drums 
having across one end a screen of 45- to 60-mesh iron, over which 
fibre brushes rotate in order to remove grit and scale from the black. 
From the bolters, the black is conveyed to a storage bin, and packed 
in 123 lb, sacks, or in 150 lb. ones if for export. 

Plants are usually built in 60 barrel units (50 lbs. black per barrel), 
and there are generally 18 buildings to an installation. A 20—25h.p. 
internal combustion gas or expansion engine is quite sufficient to 
actuate the channels and other moving parts of an installation. 

A detailed plan of a carbon-black plant is shown in Fig. 8, repro- 
duced from the Bulletin. 

Small Rotating Disc Process.—In this process, invented by A. R. 
Blood ** in 1888, and now in extensive use, the gas is burned at 
lava tips set to the number of 18 to 24 in the upper side of a ring 
of about 28 ins. diameter. The carbon black is deposited on cast- 
iron discs as shown in Fig. 9, reproduced from the Bulletin. 

The discs are 36—42 ins. in diameter, and together with the driving 
gear and pinion resemble flat umbrellas. The hopper and the 
scraper radiate from the shaft and, like the burners, are stationary. 
The discs are arranged in rows of 21 each, with 4 rows to the 
condensing building, and an independent driving shaft for each 
row of discs. One unit plant has usually 16 to 20 buildings. 

In all other respects the methods detailed in the channel process 
are followed. : 

The Plate Process.—This was invented by G. L. Cabot 2? about 
1892, and the details of the process are shown in Fig. 10, reproduced 
from the Bulletin. 

The plates on which the carbon black is deposited are 24 ft. in 

3 


34 Blacks and Pitches 


diameter, and made up of 48 segments, supported by a control 
mast and cables. These plates are stationary, though the burners 
and the scrapers rotate, making one revolution every 8 minutes. 
Usually 1265 lava tips are in use to each plate; the plates are 
surrounded by a circular building 26 ft. in diameter, constructed of 
sheet iron. The other arrangements for.conveying bolting and 
packing are just as described for the channel process. Fig. 10, 







“ 
io nS ee, 








a = 
(es am 

, ‘eS 
ty ool es 
¢. ; 


cee 
ws ht oyaehye 40g 


ez 





SRNL PTS Tee 
hi S 8 
ie fo 
i aaa 


‘ae a ae 
a se , 


ES a 
— 
Reo 
an eee een 
3 
t 
t 


| 
> 


eae Fe ae 


Enero mem mer 24". G2. - 


Fig. 8.—Carbon Black Plant in detailed Plan. 


reproduced from the Bulletin, gives a good idea of the appearance 
of the plate system in actual operation. 

The Roller or Rotating Cylinder Process.—This process, due to 
KE. R. Blood,?§ and later improved, produces the highest-priced grade 
of carbon black. The gas is burned through lava tips having a 
round perforation, instead of the usual fish tail, and a cylindrical 
flame is produced. The rollers on which the carbon black is deposited 
are 3 to 8 ft. in length and 8 ins. in diameter, and they make one 


complete revolution in 30 minutes. The scrapers are set on top of - £ 


the rollers and are continuously in operation, and 6 to 9 rollers are 
enclosed within one hood, and below the cylinders is a trough- 
shaped hopper to collect the black. 

A typical building has 196 to 288 rollers, 10,000 lava tips and 


\ 
\ ‘ 





Fia. 9.—Depositing Surface for Carbon in the Rotating-Disc Process. 






DETAIL OF COLLECTING BOX. 
Allached on underside of 


(/ 


G 


DEPAUL SUPPORTING MAST AND DRIVING MECHANISM 


Fia. 10.—Details of the Plate or Cabot Process. 








my 


Carbon Black 35 


about 24 to 32 hoods, and a like number of hoppers. The buildings 
are usually 65 to 100 ft. long and 25 to 35 ft. in width. 

Fig. 11, reproduced from the Bulletin, shows the details of this 
system. 

Various factors, such as the design of the plant, weather con- 
ditions, gas pressure and the presence of salt water or oil in the gas, 
affect the yield of carbon black obtained in the commercial methods 
of manufacture outlined. Nothing apparently is to be gained by 
the artificial cooling, using air or water, of the cooling or depositing 
surfaces of carbon-black plants. 

For a discussion of the economics of the industry the reader 
is referred to the Bulletin and to papers mentioned in the bibliography 
at the end of this chapter. 


Other Methods of making Carbon Black. 

Carbon black was first manufactured from artificial gas, and, as 
R. Irvine *® pointed out many years ago, was made in this country 
long before American natural gas was so used. 

The same quality of black was made with similar but smaller 
apparatus, ordinary town gas being used as far back as 1860. To 
produce 1 lb. of black required 1000 c. ft. of gas, and the cost was 
5s. per lb. of black obtained. Irvine ?® suggested that gas from the 
Scottish shale retorts might be used. 

One firm in this country is manufacturing carbon black from 
coke-oven gas, but beyond the fact that black is generally equal in 
quality to the American carbon black, no information is available. 
It would be interesting to know the yield of black from 1000 c. ft. 
of this gas, in view of the fact that in the case of natural gas the yield 
of black bears a close relationship to the ethane content of this 
gas. P. Lebeau and A. Damiens *° have given the composition of a 
number of samples of coke-oven gas, the ethane content being 
only 0-45 to 1:64%, which is very much lower than the recorded 
figure for any natural gas, and it seems legitimate to infer therefore 
that the yield of carbon black from coke-oven gas is much inferior 
to that from any natural gas. 

Acetylene black has been made by exploding mixtures of acetylene 
and air under pressure, the acetylene being made from the 
refuse of calcium carbide factories. Patents 34 32 33,34 have been 
effected from time to time describing the manufacture of acetylene 
black, and according to G. L. Cabot *> acetylene gas possesses the 
quality of exploding by itself, without admixture, and black has 
been made by exploding this gas under 5 atmospheres pressure, 
either by compression or by electric spark. , In those cases where 


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36 


Carbon Black 5 | 


explosion occurs in the presence of air, it has been shown that the 
acetylene not only is oxidised, but is actually dissociated. The 
black obtained is inferior in colour and strength to the carbon 
black from natural gas, but is useful where its bluish tinge gives 
it a preference in certain industries. The supply is, however, 
uncertain, and is chiefly confined to the continent of Europe. 

The yield, in the case of a small Chicago plant burning acetylene, 
as in the manufacture of carbon black from natural gas, is 11-6 lbs. 
of black per 1000 c. ft. of acetylene—a recovery of 17:3%. 

Numerous other methods have been patented for producing a 
high yield of carbon from natural gas or other hydrocarbons, the 
gas being generally split up into carbon and hydrogen in a retort 
-at high temperature in contact with refractory material. Mention 
may be made in this connection of the work of R. H. Brownlee and 
R. H. Uhlinger,®® of Szarvasy,?’ of McCourt and Ellis,3* of W. G. 
Laird,®® and of a recent attempt of J. A. McGuire,*® who causes 
chlorine to react with an excess of hydrocarbon. No great quan- 
tities of usable carbon black have been made by any of these processes. 


Properties of Carbon Blacks. 


All the earbon blacks are very intense in colour, glossy, whether 
rubbed dry or in varnish, and have an extraordinary mixing strength. 
They mix with water by simply shaking them with it, though lamp- 
black usually will not, and this is a convenient method of distinction. 

Carbon blacks generally are hygroscopic, and some blacks will 
absorb as much as 15% of moisture. Carbon black contains con- 
siderable quantities of carbon monoxide, carbon dioxide and oxygen, 
the latter probably being present in some sort of loose combination as 
** fixed oxygen,” and the carbon dioxide may be present to an extent 
equal to 1% of the weight of moisture present. 

The specific gravity of carbon black varies from 1-8 to 2-1, and 
its determination requires some little care in order to eliminate the 
air bubbles always enclosed in the pigment. The determination 
may be carried out in the usual type of specific gravity bottle, which 
is weighed empty, full of distilled water and then full of the dry 
pigment. The bottle containing the pigment is then filled with 
distilled water and the enclosed air bubbles are removed by heating 
and until the pigment is thoroughly wetted. The bottle and con- 
tents are then brought to a temperature of 15-5° C., and additional 
water is added if necessary, until the bottle is quite full, and then 
weighed again. The ratio of the weight of the pigment to the weight 
of water displaced by it gives the true specific gravity of the pigment. 


38 Blacks and Pitches 


When making this determination for lampblack, it is preferable 
to use benzol or some liquid which will completely wet the pigment. 
Gardner *1 has drawn attention to the difficulties to be encountered 
in determining the specific gravity of fine pigments and indicated 
how these difficulties may be overcome. 

The present writer ** has examined a number of genuine carbon 
blacks, with the results recorded below : 


Tasie VIII. 
Analyses of Carbon Blacks. 





~The acetone extract of the above blacks was a mere trace—too 
small to record in the data. 

The volatile impurities in carbon black may be removed, accord- 
ing to J. C. Morrell,*® by heating the black to pie NE es C. in an 
iron crucible under suitable conditions. 

In Table IX. are details of some very sontnles analyses of carbon 
blacks due to W. A. Selvig. 

The determination of volatile matter is carried out in the same 
way as outlined in any of the well-known volumes dealing with the 
analysis of fuel, and need not be detailed here. The U.S. Bureau of 
Mines recommends for the determination of moisture, ash, and ace- 
tone extract the following standard methods, full details of which 
will be found elsewhere, due to F. M. Stanton and A. C. Fieldner.** 


Moisture—‘‘ A one-gram sample of the black is placed in a 
weighed porcelain crucible, and heated for 1 hour at 105°C. in 
a constant temperature oven in circulating dry air. The crucible 
is then removed from the oven, covered, and cooled in a desiccator 
over sulphuric acid. The lossi in weight multiplied by 100 is recorded 
as the percentage of moisture.”’ 

Ash.—* The crucible containing the residue from the moisture 
determination is heated gradually with a Meker burner, or better 
in a muffle furnace, to about 750°C. or to a cherry-red. Ignition 
is continued until all the particles of carbon have disappeared. The 


crucible is then cooled in a desiccator and weighed, after which it is 
heated again for 15 minutes, cooled in a desiccator, and re-weighed. 
If the change in weight is more than 0-0002 gram, the process is 
repeated, until successive weighings are constant to this figure. 
The weight of the crucible and ash minus the weight of the crucible 


Carbon Black 


is taken as the weight of the ash.”’ 


| | Tasre IX. : 
Analyses of Carbon Blacks, Lampblacks and other Blacks (Selvig). 


Calarific value. 


Method of manufacture. 


Manufacturer. 


Brand 


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and ash free. 


@ The form of analysis is denoted by number as follows: 1=sample as received; 2=dried at a temperature of 105° C.; 3=moisture 


Acetone Extract—‘ A two-gram sample is weighed into an 


alundum or paper extraction thimble of 20 c.c. capacity and the 
extraction carried out for 1 hour, using any standard apparatus of 
The weight of the residue after evaporation 


the Soxhlet type. . 
The extract for a 


of the acetone is taken as the acetone extract. 


pure carbon black is usually zero.” 


40 Blacks and Pitches 


The estimated distribution of carbon black per annum produced 
in the United States is : 


Lbs. 
Rubber industry : ’ ; . 20,000,000 
Printer’s ink ; : : : : 10,000,000 
Export ; ‘ 8,000,000 
Stove polish ; : 4,000,000 
Phonograph records. ; 500,000 
Other Uses. % : ; : : 1,000,000 


Under other uses are paint, carbon paper, type ribbon, tarpaulins, 
carriage cloth, black leather, paper, bookbinder’s board, shoe polish, 
electric composition insulators, celluloid, buttons, etc. Considerable 
quantities are shipped to England, France, Japan and China. 
During pre-war times one-third of the annual production was 
exported. 

Generally speaking, it may be said that carbon black is preferable 
for black printing ink, stove polish and vulcanised rubber, lamp- 
black being the better pigment, according to G. L. Cabot, for colour- 
ing oilcloth, leather and rubber, other than vulcanised, and generally 
for paint, although carbon black is preferable for certain kinds of 
paint and varnish. For further information, the reader may be 
referred to a paper by Perrott and Thiessen.*® 


REFERENCES. 


19 J, Soc. Chem. Ind., 1894, 18, 128. ?° IT: 16 U.S. Dept. of the Interior, 
U.S. Geological Survey, 1921, p. 145. 21 Monthly Report of Investigations, 
Bureau of Mines, U.S. Dept. of the Interior, March 1920. 72 “‘ The Sampling 
and Examination of Mine Gases and Natural Gas,’’ G. A. Burrell and F. M. 
Seibert, Bulletin 42, U.S. Bureau of Mines, 1913. * ‘“‘ Testing Natural Gas 
for Carbon Black,’’ Chem. and Met. Hng., 1920, Feb. 25th. ?4 W. A. Bone, 
Phil. Trans. Royal Soc., 1915, 215, 275. 5 J. Chem. Soc., 1916, 109, 160. 
26 U.S. Patent 387,487 of 1888. 27 U.S. Patent 468,510 of 1892. 28 U.S. 
Patent 269,378 of 1882. 9 J. Soc. Chem. Ind., 1894, 18, 130. °° Compt. 
rend., 1920, 171, 1385. °1 Morehead, U.S. Patents 779,728 and 986,489. 
82 Pictet, English Patent 24,256 of 1910. °% Wegelin, German Patent 
201,262 of 1907. %4 Bosch, German Patent 270,199 of 1913. °° ** Lamp- 
black and Carbon Black,” 8th International Congress of Applied Chemistry, 
1912, 12, 13. °° U.S. Patents 1,168,931, 1,265,043, and 1,478,730. %* U.S. 
Patent 1,199,220. °8 U.S. Patent 1,276,385. %®® U.S. Patent 1,490,469. 
40 U.S. Patent 1,498,924. 41 “‘ Fineness and Bulk of Pigments,’ H. A. 
Gardner, Circular 148, U.S. Paint Manufacturers’ Association, 1922. 4%. Un- 
published results. 43 U.S. Patent, 1,359,091 of 1920. 44 F. M. Stanton 
and A. C. Fieldner, ‘“‘ Methods of Analysing Coal and Coke,”’ Tech. Paper 8, 
U.S. Bureau of Mines, 1913. 4° ‘‘ Carbon Black: Its Properties and Uses,” 
J. Ind. Hing. Chem., April, 1920. 


al 


Bibliography—Carbon Black. 


“* Efficiency of Carbon Black Plants,’’ Chemical and Metallurgical Engineer- 
ing, New York, July 5th, 1922. ‘‘ Startling Waste of Gas in Carbon Plants 
is Shown in Report,’’ American Gas Journal, New York, May 27th, 1922. 
** Carbon Black Industry in Louisiana,’’ Chemical Age, New York, December, 


Carbon Black 4] 


1920. ‘‘Carbon Black Industry,” Manufacturers’ Record, Baltimore, Md., 
February 24th, 1921. ‘‘ New Idea in Carbon,” Petroleum Age, Chicago, 
Illinois, January, 1921 (relates to use of electrical precipitation process). 
“Carbon Residue from Oil-gas Manufacture used for every Purpose for 
which Coal is Utilised,” American Gas Journal, January 20th, 1917. 
*“Channel Process for making Carbon Black,’’ Chemical and Metallurgical 
Engineering, October 13th, 1920. ‘‘ Disk, Plate and Cylinder Processes for the 
Production of Carbon Black,”’ zbid., October 20th, 1920. ‘‘ Louisiana Natural 
Gas and Carbon Black Manufactures,’’ Chemical Age, September, 1921 
*“Demand for Carbon Black,” Gas Age, April 10th, 1920. ‘‘ Carbon Black, 
a Natural Gas Product,” Scientific American, January 1920. ‘‘ The Carbon 
Black Industry,’’ Chamber of Commerce Journal, May 16th, 1924. J.B. Garner, 
““The Chemical Possibilities of Carbon Black,” Proc. Nat. Gas Assocn. of 
America, 1918,10, 136. ‘‘ Thermatomic Carbon Black,’’ Chem. Trade Journal, 
1924, 75, 712. ‘‘ Chemistry and Physics of Carbon Black,’ G. L. Cabot, 
Paint, Oil and Chem. Rev., 1924, 78, No. 21. ‘‘Manufacture of Gas Black,”’ 
E. H. Thomas, U.S. Patent 1,514,638 of 1924. A. Bonnington, U.S. Patent 
1,515,333 of 1924. 


CHAPTER V 
LAMPBLACK 
Methods of Production—Properties, Uses and Analyses. 


LAMPBLACK is the soot or impalpable powder obtained from the smoke 
arising during the incomplete combustion of various carbonaceous 
substances such as vegetable and animal oils, pinewood and resinous 
materials. Soot has from time immemorial been used in painting 
and colouring a variety of objects, and it was the basis of the earliest 
known inks. The Chinese were probably the first to make it on an 
extensive scale for the manufacture of Chinese inks as known to 
the ancients. The method of manufacture was very primitive— 
and still is in China—the pigment being made by igniting resinous 
material in a pot in a closed room and leaving the material to burn 
itself out through lack of proper air supply. 

Neither the yield nor the quality of the black could be considered 
satisfactory when produced in this way, and ordinary soot from the 
chimney back, once in common use as a pigment, is now discarded as 
being too impure owing to the amount of gritty and empyreumatic 
matter it contains, together with other impurities, and by reason of 
inferior colouring power. 

The German method at one time was to burn resinous woods in a 
closed furnace and collect on woollen cloths, exposed to the smoke 
emitted, the resulting black. 

In modern methods of manufacture the starting point is the 
dead oil of coal-tar works, an oil containing a large amount of - 
naphthalene, some phenol and various aromatic hydrocarbons, 
particularly suited to the manufacture of lampblack by reason of the 
large percentage of carbon contained therein. These compounds, 
burnt in an insufficient supply of air, yield from 15 to 35% of their 
weight in the form of lampblack by deposition in suitably arranged 
chambers. 

According to Cabot,®> the quality of the black is determined by 
the size and shape of the furnaces in which the oil is burned, by 
the heat to which it is subjected during the progress of the manu- 
facturing operation, by the position in which the black is deposited, 
and by the care exercised in selection of the raw materials employed. 

The oil is normally allowed to flow in a sluggish stream into an 
earthenware or iron pot or pan, in which burning occurs, and from ~ 
which the smoke passes through flues into the chambers in which 
the black is deposited. 

The best grades of black, generally speaking, are obtained in 
furnaces of moderate size so built that the black is practically 

42 , 


Lampblack An 


calcined at the time it is deposited and carries down with it but 
little empyreumatic matter. The products of combustion are 
usually carried through a series of chambers, in which are partition 
walls, and the gases charged with lampblack are thus compelled to 
follow a tortuous path. The baffling effect of the partitions not only 
facilitates the deposition of the black, but may increase the per- 
centage of deposition, though, of course, the placing of partitions can 
be overdone, and then the speed at which the gaseous products are 
impelled through the chambers becomes too great, leading to loss of 
black. 


~ 


VLA dL Lb hhh hh Lb b hf pitdddldlde,  plddebdbeke. 
3a g 
~ 


CSS 


NNN 


SY 
SS 


BS 


SSS 
SSS) 
SEES 
ASE ASRRRA NAS ERNRRRARRRANS, 
AAAAASARRRRRAARARRAESSARRRRRRS 


\ 


Z “or y 


N 


Ns 


A. Elevation. 


ULLLLLLILIILA MM MY f bhtddt tty 





Fie. 12.—Arrangement of a Lampblack Plant. 


The charging of lampblack furnaces must be performed quickly, 
to minimise the possibility of entry of large volumes of air into the 
furnaces and chambers owing to the risk of formation of explosive 
mixtures of air and the unconsumed combustible gases in the 
chambers or collectors, as they are also termed. The furnaces are 
kept at work for several days and then the chambers are allowed to 
cool gradually, care being necessary to admit the air only at a rate 
sufficient to remove any combustible gases from the chambers. 
Lampblack is very strongly pyrophoric, and therefore the greatest 
care is necessary in cooling it, for until it is cool it cannot be removed 
from the chambers. 

The accompanying sketches (Fig. 12) indicate, in plan and 
elevation, the type of arrangement of a lampblack plant for securing 


4.4. Blacks and Pitches 


efficient deposition of the black. From time to time mechanical 
devices have been used in the form of stirrers to churn the air and 
cause the condensation of the smoke in masses sufficiently large for 
it to deposit itself. 

Resin, resinous woods, tar and pitches are still to a small extent 
used in the manufacture of lampblack, though the product is said not 
to be so good as that from the dead oil of tar. The manufacture 
from hull bran has been described by Hershmann,*® from peat by 
J. E. Smith,4? and from coal-tar pitch by A. C. Evans and others.*® 
By the incomplete combustion of oil,*® the burning of oil fuel,°° and 
in several other ways based on the use of coal tar,>) 5? lampblack 
may be obtained. 


Properties of Lampblack. 


Usually this contains about 80% of amorphous carbon, the rest 
being traces of resinous oils, empyreumatic matter, moisture, traces 
of adsorbed carbon dioxide and carbon monoxide and grit from the 
floors and walls of the collecting chambers. In contrast to carbon 
black, it has a grey hue. Its true specific gravity is 1-7 to 1:8 
usually, and though it mixes well with oil and varnish, it does not 
generally mix with water. 

The contrasting properties and qualities of lampblack and carbon 
black have been described by G. L. Cabot,1* 35 and from microscopic 
appearance it seems likely that in their structure.these two black 
pigments differ from one another. As an explanation of this, 
Perrott ? has put forward the suggestion that the difference may be 
due partly to the fact that as lampblack is made from a complex 
mixture of carbon compounds, each with its own optimum tem- 
perature of decomposition, a uniform product is less likely than 
might be expected in the case of carbon black produced from such a 
relatively simple raw material as natural gas. 

The very best qualities of lampblack, known technically as 
vegetable black, are finer and softer in texture than ordinary lamp- 
black, this vegetable black being the black deposited farthest away 
from the burning raw material. Such vegetable black is blacker 
than the commoner grade of lampblack, and is lower in ash and oily 
and empyreumatic matters. The term “ vegetable black” is due 
to the circumstance that at one time the finer seed oils were used to 
produce this pigment. Tables X and XI (reprinted from Tables 
XIV and XV of Bulletin, 192) record the analyses of some lamp- 
blacks, particulars for other black pigments being given for 
contrast. 


Lampblack 


TABLE X, 


Analyses of Carbon Blacks. 





Lon Lon ang Short Short Short 
blac blac blac black black black 
No. 1. No. 2. No. 3. No. 1. No. 2. No. 3. 


en 








nS ON Se re ea eee 3. 56 713 30 2.25 3. 02 3.12 
Wiolative MIALtGF. 5 oo uc nee aswescdcecc 11. 99 13, 41 10. 49 5. 60 5. 48 5. 58 
RMEMRE Pee eras otra oa. sratars aise geaw'y 84. 40 79. 44 84. 16 92.13 91, 47 91. 22 
Pe a cereh ne rkewnavecs chs aswecavat tine +05 02 14 02 03 . 08 
ULTIMATE ANALYSIS (AS RECEIVED). 
CNC eet se a 1.19 1, 32 1.11 74 . 88 1.05 
tie Se ne oa aie 88. 17 84. 56 &7. 98 94. 78 93. 50 93. 63 
IO OES NE Sa aa 04 . 04 08 . 00 04 .05 
I ER Ae LE pica Sinn ciceb e's oe wae 10, 54 14. 00 10, 68 4. 37 & 25 5.19 
PERMA 2 oar Pg eink baw clceh wattas one cedSe > 01 . 06 Ol 00 30 00 
OL A CeO eae a See - 02 -14 02 03 - 08 
ULTIMATE ANALYSIS (MOISTURE FREE). 
MMO eE ae con wn tcrrcye a oees 82 57 «55 50 52 72 
Te oh TopRank ee 91. 42 91. 05 92, 91 O56, 86 96, 41 06, 64 
LE VEE NEE ee eee See 04 07) - 08 . 08 04 - 05 
ea is BEE 2 EER ee 7. 68 8, 28 6, 36 2. 43 2, 68 2. 51 
LS eee a a ee eee - 01 . 06 91 . 00 -3l . 00 
eee ON nas R ci SaaS USL ia select gra wna 05 . 02 -15 02 . 08 , 08 
True specific gravity. .............-...00-- 80 1, 78 1, 88 1,85 1. 80 1,78 
TABLE XI. 


Analyses of Lampblacks and other Blacks. 













Carbon from 

















! f 
Lampblaeck. Willow! W baer - 
Bone | Vine . 
black. | black. | CBS! | ,pul 
: *! coal. | black. 






No. 1. | No. 2. 







PROXIMATE ANALYSIS. 





IS a a a a 3. 88 
Wr OUBPIe MIAELET. oo 5 a as orcs weceeae 10. 92 
Pimed Carbon ie. ..5 cose es ewks ceva 2. 68 

OL Re ane 82. $2 





LU, Eee go ee a oe ebz 13 - 83 
Geren Aon win Sew ieierac cea 87. 62 87, 84 & 64 
eM ete hea oe liciasncwia eaeee e's cay ie a - 00 1, 06 
ON geo ang Liye Sam ld ssc ove 1.18 9. 95 6. 8A 
MERI EE a ee he anche dee caccese oT 64 08 
RRNA fe esi Son's a minivieis: dae . 00 -06 | 82.52 






RE MOPN oe Oe. So Sc in now pils dcd'ateie x 1, 20 47 
NS Oe ES are eae ee 98, 00 90. 67 8. 99 
MOREE GEP Ta phaseio iS aia's ys visti wis piace aren =k vie od . 60 1.10 
UGE es Ses 84 7.41 3.53 
ER hienciids uy peewee pnnsincecse 57 66 . 06 
Ie 5 ee oe = a . 00 06 | 85.85 
(ACETONE OXtVACt........sicsacevescnssee - 





45 


46 Blacks and Pitches 


REFERENCES. 


46 U.S. Patent 1,188,936. 47 U.S. Patent, 916,049. 4% U.S. Patent 
1,175,732, of 1916. 4% Lampblack, Ltd., English Patent 17,223 of 1912. 
50 Franz Maiser, German Patents 203,711 of 1909 and 288,990 of 1914. 
51 Riitgerswerke A.-G., German Patents 208,600 of 1908 and 383,922 of 1922. 
52 French Patent 480,487 of 1916. 


Bibliography—Lampblack. 
‘“‘Colour Manufacture,” Zerr, Riibencamp and Mayer, Charles Griffin 
& Co., 1908. T. W. 8. Hutchins, Manufacture of Lampblack, U.S. Patent 
1,309,070 of 1919. W. H. Frost, U.S. Patent 1,438,032 of 1922. J. G. 
Bearn, ‘**'The Chemistry of Paints, Pigments and Varnishes,” Chapter XII, 
Ernest Benn, Limited, London, 1923. 


CHAPTER VI 
BLACK PIGMENTS IN PAINT MANUFACTURE 


Consideration of the Physical Properties Involved—vVarious Uses of Black 
Pigment Paints—British Standard Specification for Carbon Black. 


BLACK pigments find extensive use in various branches of the paint 
industry, and reference has already been made in earlier chapters 
to the use of metallic black pigments and particularly of graphite 
in this connection. The evaluation of black pigments according 
to their physical properties is of prime importance when considering 
the suitability of these pigments in the manufacture of paints, and 
the chief physical properties we must look at are as follows :— 

1. Specific gravity. 
. Fineness. 
. Oil absorption. 
. Tinting strength. 
. Colour. 

Chemical properties have been discussed in the earlier chapters 
and need not be touched upon again here. Such physical charac- ~ 
teristics as covering power, hiding power, opacity, apply to pig- 
ments only when viewed in conjunction with paint media, and 
their study therefore does not really concern us here. 

1. Specific Gravity—The method of estimating this has been 
outlined in Chapter III, and for a pigment in a fine state of division 
is not quite as simple an operation as may be imagined. The sources 
of error lie in the difficulty of entirely removing entangled air 
and the difficulty of ensuring that the finest portions of the pigment 
are completely “ wetted,’ and it is therefore important that a 
proper vehicle should be selected in which to determine the specific 
gravity. In this connection the reader is referred to a paper by 
Nuttall *? on the “ wetting power ” of a liquid. 

Increasing attention has been paid in recent years to the specific 
gravity of pigments, owing to the bearing this has on the volume 
of mixed paints, and also on the behaviour of pigments when sus- 
pended in liquid media. In some measure also there is a connection 
between the specific gravity of a pigment and the amount of oil 
required to grind the pigment into a uniform stiff paste, but this 
characteristic is more properly correlated with fineness.? 


Cu Bm OG bo 


Average Specific Gravity of Black Pigments with others for Comparison 


EGIIED fay cieis dissin evih viens sine ses 2-46 Fied, leeth- visuyinseed sth t-gee 8-80 
RA a ais scaxvepesnsese seins 2-46 LARS GNI oo an nvantankaay hee 5-60 
MEIGS oye ckcccacessscvvetse 2-35 White lead... igs... nes sesers ee 6-60 
Lamp black (vegetable Barytessiss sd cia aoe 4-45 

ES ap ey aE i ape A 1:78 Ultramarine blue ............ 2:50 
ERICA ACK Sib Sis0k chesnceals 1-80 


47 


48 Blacks and Pitches 


2. Fineness.—This as applied to pigments is usually understood 
to refer to the degree of subdivision of the particles, and has an 
important bearing on the paint industry. A certain degree of fine- 
ness is, of course, essential before the mixture of solid pigment 
with its liquid medium can be spread uniformly over a surface; 
moreover, the hiding power of a pigment is inversely proportional 
to the diameter of the particles, and furthermore the finer the 
particles of a given pigment when mixed to form a paint, the greater 
is its covering power. 

The study of the ultimate size of particles, the determination of 
their size and the application of the results to the study of problems 
in the paint trade have engaged the attention of C. A. Klein and 
W. Hulme *4 and C. A. Klein and J. Parrish,®> °§ whose conclusions 
have appeared in recent publications. The chief methods which 
have been proposed for determination of particle size are: 


(i) Screening followed by elutriation or sedimentation. 

(ii) Direct examination under a microscope by a method 
due to Green.5’ A photomicrograph of a carefully prepared 
mounted sample is taken, and this is further enlarged by means 
of a stereopticon, the measurement being made of the particles 
on the screen by means of a millimetre scale. Green introduces 
a number of corrections in order to get a reliable value, but 
several objections have been made to some of his conclusions. 

(iii) A centrifugal method due to Svedberg and Nichols.* 

(iv) Specific gravity suspension method due to Wiegner.®*® 

(v) Air flotation. 


Space forbids any full treatment of the subject here, as we are 


concerned mainly with results obtained for black pigments and the 
bearing these results have on paint manufacture. According to the 
table by Klein and Parrish,®*° carbon black particles lie between 20 
and 10uu (lu = 10° metre), with a limiting size of luu. Now it is 
extremely unlikely that such a fine state of subdivision characterises 
those black pigments which after manufacture require mechanical 
srinding, such as the various charcoals, graphite, bone black, drop 
black; the bearing of this will be seen later. 

Klein and Parrish °* have pointed out the bearing of particle 
size, the effect of grinding and the influence of air-surround of pig- 
ments on the bulking value, which is of such importance in the paint 
industry. The figures given in Table XII, taken from their paper, 
are of interest, particularly the figures relating to oil absorption. 

The authors discuss the various factors bearing on the bulking 


os 


Black Pigments in Paint Manufacture 49 


value, and particularly mention the influence of the air-surround of 
the particles, which in the case of carbon black in the packed condition 
amounts to 80%. 


TaBLe XII. 
Bulking Value and Oil Absorption of some Pigments. 


Bulking value 


Ibs./¢. ft. Air voids | Ot! absorp- 

) tion in gms. 

Pigment. for packed ac oil Be 

Loose. Packed. | Condition. pi Sait 

White lead A ......... 44 125 71 12 
POOR ICR Bones ccenesees 103 233 58 8 
TARPS Ue vevevieesscakies 49 140 49 i3 
fear pon Jlaels 5.055 sess. 13 3 80 150 
Ng BO ee 19 53 58 - 46 


3. Oil Absorption.—At the present time consideration of the 
amount of oil or other medium required to convert a pigment into 
a paste ready for application in painting is an important matter, 
and is spoken of generally as the “ oil absorption ”’ of the pigment, 
though this term is capable of a varied interpretation, as Cruick- 
shank Smith points out. The exact method of determination of this 
property leaves much to be desired. Calbeck ® distinguishes be- 
tween primary and secondary oil absorption of pigments, the former 
being the proportion of oil required to make a stiff paste, whilst 
the latter refers to the additional amount of oil necessary to produce 
a mixture of painting consistency. This author mentions the follow- 
ing factors as determining the oil absorption: (1) air voids to be 
filled, (2) wetting power of the oil, (3) nature of the surface of the 
solid particles, (4) specific surface or fineness of the pigment, 
(5) geometrical arrangement of the solid particles in the paste or 
paint. 

Gardner * has given some figures showing the percentage of 
oil required for grinding pigments into average paste form, viz. : 
Carbon black 82%, lampblack, 72%, drop (bone) black, 60%, bone 
black 40%, graphite (pure), 40%, and for contrast one may cite 
white lead (sublimed), 10%, blanc fixé, 30%, barytes (natural), 9%, 
terra alba (gypsum), 22%. 

4, Tinting Strength—The tinting strength of a pigment is a most 
important desideratum to the paint manufacturer, and it is in virtue 


50 Blacks and Pitches 


of their tinctorial properties that pigments transmit their own specific 
hue or colour to other pigments or materials incorporated with them. 
The tinting strength as applied to blacks is the measure of their 
ability to impart a black hue to a definite weight of a standard white 
pigment. In testing any given black it is the rule to compare its 
tinctorial properties with a standard black pigment, and the following 
procedure is that proposed in connection with the use of American 
carbon black as a paint pigment.? 

In making the test, weigh out accurately 0-100 gram of the black 
to be tested, and 10-0 grams of standard zinc white kept specifically 
for such a test as this. Transfer to a glass or marble slab, and add 
from a burette exactly 3-5 c.c. of refined linseed oil. Mix with a 
palette knife, and rub out thoroughly with the knife until no streaki- 
ness is observed when successive small portions are spread on a clear 
piece of window glass and viewed from the upper side. Ten minutes 
is usually the time for this operation. Follow the same procedure 
with the standard black. Then spread a small amount of each 
mixing side by side on a clear glass, such as a microscope object glass. | 
Examination of the samples from the other side of the glass, par- 
ticularly at the line where they overlap, will show a difference of 
tinting strength should any exist. 

To make a quantitative estimation of the tinting strength of the 
sample as compared with the standard, more white is added to the 
stronger mixing until the colours match. A new sample of the 
stronger black is then weighed out, using the calculated amount 
of zinc white, and the process is repeated until mixes of the same 
colour are obtained. If, for example, it was necessary to mix 15 
grams of zinc white with 0-1 gram of the standard to match a mixture 
of 10 grams of zinc white and 0-1 gram of the sample, the sample 
has 662% the strength of the standard. 

5. Colour.—By the term colour is meant the relative blackness 
of the material when mixed with oil. In making the colour test, 
0-3 gram of each of the blacks to be compared is added to each of a 
like number of portions of 1-3 ¢c.c. of refined linseed oil from a burette. 
Mix thoroughly by means of a palette knife, spread side by side on a 
slip of glass, and compare the relative colour by viewing from the 
upper side of the glass. 

The measurement of the colour of a pigment in terms of some 
agreed standards is possible by such means as the use of the Tinto- 
meter (Lovibond), the Colourmeter and other means, to which 
considerable attention has been paid in recent years. The reader 
is referred to the more recent volumes on colour manufacture and 


Black Pigments in Paint Manufacture 51 


colour testing for a fuller insight into the details of colour 
measurement (cf. Klein and Aston’s volumes). 

In considering the uses of the black pigments in paint-making, the 
purpose for which the paint is intended is of importance, and 
Cruickshank Smith mentions the following uses to which such a paint 
may be applied : 


(a) Decorative work requiring a jet-black used chiefly as a 
self-colour ; 

(6) Tinting or staining, requiring a finely-ground and very 
strong paint suitable for making grey or slate-coloured tones; 

(c) Protection of wood, iron or stone, or as an important 
ingredient in paints to be used in protecting one or other of these 
surfaces. 


For decorative work alone, bone black is strongly favoured, carbon 
black being added sometimes to secure depth of colour. Often, 
however, such pigments are adulterated with barytes and whiting 
for cheapness. 

Black paints for tinting and staining purposes must generally 
be lampblack or carbon black, and in conjunction with a white base 
the former gives a bluish-grey tone and the latter a brownish-grey 
tone. Blacks vary in colour and in their tinting strength—the less 
volatile matter a black contains the blacker its colour. But the 
tinting strength of blacks high in volatile matter is usually higher 
than that of blacks containing more free carbon. This fact may be 
due to the way in which the volatile matter is dispersed through the 
black; this point will be discussed more fully in the next chapter 
in connection with the use of blacks as ink pigments. 

Carbon black and lampblack absorb far more oil in grinding than 
is the case with mineral and bone blacks; this is partly on account 
of their finer state of subdivision, but against this must be set the 
fact that paints from the former pigments have, in consequence of this 
finer state of subdivision, greater hiding power. Generally also the 
former blacks are unsurpassed for use in making certain \black 
varnishes on account of their superior tinting strength; carbon 
black has three times the tinting strength of some of the charcoal 
blacks, such as one from ground coconut charcoal. 

As protective coverings, black paints are not used for general 
purposes, except in the case of graphite, which has been mentioned 
in this connection in Chapter II. In the preparation of black dis- 
tempers for stone and wood, however, and in the manufacture of 
stove polishes, both carbon black and lampblack find great use. 


52 Blacks and Pitches 


The so-called grinding in oil of the blacks, or, more properly 
speaking, their incorporation in the oil or paint medium, can be carried 
out in the ordinary granite triple-roller paint mill in the case of 
paints which contain the relatively coarser mineral, bone or charcoal 
blacks. Where very fine lampblack or carbon black is concerned, 
the ordinary granite triple-roller mill is useless. Rollers with a 
very smooth face are used, and these are usually enclosed under 
a hood or cover, so that loss of pigment, owing to its extreme fine- 
ness, is prevented. The author has experienced cases where such 
covering was necessary even in the use of very finely-ground vege- 
table charcoal. 

The following tests have been suggested ? in connection with the 
use of carbon black as a paint pigment : 


Carbon Black for Paint Manufacture. 


Chemical tests. Physical tests. 
Moisture ......... less than 5% Tinting strength ...... not less than 
PARED ons o chil axa chen less than 1-:25% 95% of the 
strength of 
standard. 


In connection with the use of carbon black as a pigment in air- 
craft manufacture, the following specification is extracted, by the 
kind permission of the British Engineering Standards Association, 
from their Report No. D. 30, November, 1921, official copies of 
which can be obtained from the Secretary of the Association, 28 
Victoria Street, Westminster, 8.W.1, price 2d., post free. 


BRITISH ENGINEERING STANDARDS ASSOCIATION 
British Standard Specification for Avrrcraft Material. 


CARBON BLACK 


1. Description.—The material shall consist of gas carbon black, 
containing not less than 96% of carbon. 

2. State of Division—The material shall be in a fine state of 
division, uniform in character and free from gritty particles. Five 
parts of the pigment shall grind to a stiff paste with 4 parts of 
castor oil (British Standard Specification 2 D. 5). 

3. Moisture, etc—The loss in weight on heating in an oven at 
100° C, (212° F.) for 1 hour shall not exceed 3%. 

4. Matter Soluble in Water.—The material shall contain not more 
than 0-1% of matter soluble in water and the aqueous extract shall 
show no acid reaction to methyl orange. 

The test shall be carried out as described in Appendix I. 

5, Ether Extract.—The material shall contain not more than 0- 5%, 


Black Pigments in Paint Manufacture 53 


of matter soluble in methylated ether (sp. gr. 0-720). This shall be 
determined by extraction in a Soxhlet apparatus for 2 hours. 

6. Ash.—The amount of ash left on ignition shall not exceed 
oy 

7. Colour—The colour of the material shall closely match 
that of the Standard,* when determined by the method given in 
Appendix II. 


Note.—By “match” in the above clause, shall be understood approxi- 
mately matching when compared with the Standard in diffused daylight. 


8. Tinting Strength.—The tinting strength of the pigment shall 


be not inferior to that of the Standard,* when determined by the 
method described in Appendix III. 


APPENDIX I. 
Method for the Estimation of Matter Soluble in Water. 


Two grams of the material shall be moistened with alcohol and 
then boiled for 5 minutes with 200 c.c. of neutral distilled water and 
filtered. The reaction of the filtrate shall be determined towards 
methyl orange. An aliquot part of the filtrate shall then be 
evaporated to dryness and the residue weighed. 


AppEnpDIx II. 
Method for the Determination of Colour. 


Four parts of the pigment shall be ground to a paste with 3 
parts of castor oil (British Standard Specification 2 D. 5). 3:5 
grams shall then be thinned with 50 c.c. of the following nitro- 
cellulose medium, and the resulting product brushed on doped 
Linen Aeroplane Fabric (British Standard Specification 3 F. 1). 


Nitro-cellulose syrup, British Standard Specification 2 D. 8. 23-2 grams 


Butyl acetate pe ne ie oD: €s L642ec. 
Alcohol # << a 2 Dobe 1b wee 
Benzol a ot A 2 D. 10. Is sec: 
Acetone = a “e 2D 22, 29s 


APPENDIX III. 
Method for the Determination of Tinting Strength. 


One part of the pigment shall be mixed with 80 parts of zinc 
oxide (British Standard Specification D. 27) and ground to a paste 
with 50 parts of castor oil (British Standard Specification 2 D. 5). 


This Specification was adopted by the Sectional Aircraft Com- 
mittee on the 21st October, 1921, and approved on behalf of the 
Main Committee on the 5th November, 1921. 


* The Standard consists of a piece of doped and varnished fabric pre- 
pared as described in Appendix II, which can be obtained on application to 
the Superintendent, Royal Aircraft Establishment, Farnborough. 


54. Blacks and Pitches 


When considering artists’ pigments, the qualities most desirable 
are permanence, brilliance, purity of tone; and permanence is, of 
course, often a matter of conditions. In manufacturing the artists’ 
black pigments the most frequently used blacks are carbon black, 
lampblack and bone black.®! 


REFERENCES. 


53 “ Industrial Applications of Wetting Power,’ 5th Colloid Report, Bri°. 
Assoc. Adv. Sci., 1923, 38. 54 Journ. Owl and Colour Chem. Assoc., 1920, 
21, Vol. III. °° Jbid., 1924, 45, Vol. VII. *°* Jbid., 1924, 46, Vol. VIL. 
5? Journ. Franklin Institute, 1921, 192, 637. 58 Svedberg and Nichols, 
Journ. Amer. Chem. Soc., 1923, 45, 2910. 5 Wiegner, Landw. Versuchsst., 
1918, 91, 41. ® ‘* The Oil Absorption of Pigments,’ Calbeck, Chem. Met. 
Eing., 1924, 31, 377. 61 May, Chem. and Industry, 1924, 48, 82. 


Bibliography—Blacks as Paint Pigments. 


‘* Determination of Distribution of Particle Size,’ Kelly, J. Ind. Eng. 
Chem., 1924, 16, 928. J. Parrish (communication to discussion), Journ. Ol 
and Colour Chem. Assoc., 1925, 55, Vol. VIII. ‘‘Numerical Determination of 
the Fineness of Pigments,’ Werl, Moniteur de la Peinture, 1924, No. 116, 309. 
“The Chemistry and Technology of Paints,” M. Tech., 1916. ‘‘ Modern 
Pigments and their Vehicles,” Maire, 1908. Papers on the Measurement of 
Colour, Journ. Oil and Colour Chem. Assoc., 1921, 27, Vol. IV. Jbid., 1922, 
36, Vol. V. 


CHAPTER VII 
BLACK PIGMENTS FOR INK MANUFACTURE 


Different Classes of Work requiring Printing Ink—Properties of Blacks— 
Long and Short Blacks—Chemical, Physical and Practical Tests on 
Printing Ink Blacks—Some Photomicrographs of Ink Pigments. 


It seems probable that the very earliest known inks had lampblack 
or some similar form of carbon as their base; all the ancient 
Egyptian inks appear to have been essentially carbonaceous in 
character. A. Lucas ® has examined the remains of ink of the 
sixteenth century B.c., and shown it to be of carbon basis. Accord- 
ing to Chinese historians, Chinese, or Indian ink as we term it, 
was made as far back as between 2697 B.c. and 2597 B.c. Vitru- 
vius,®* the Roman engineer (30 B.c.—a.D. 14), describes the prepara- 
tion of an ink for decorative purposes, the soot from pitch-pine being 
the basis. Gradually, however, the transition from carbon inks to 
those made from gall nuts and iron salts took place in Europe, and 
this transition was probably complete by the Middle Ages so far as 
inks for writing purposes are concerned. For a full account, how- 
ever, of the development of the ink-making industry from the earliest 
times to the present day the reader must turn to Mitchell and 
Hepworth.*4 

With the invention of the printing press and its introduction 
into England by Caxton, lampblack as a pigment for printing ink 
came into universal use, and was used exclusively for this purpose 
until the advent of carbon black about 1864, since which date the 
latter pigment has been used to an increasing extent, and is now 
the principal pigment for black printing ink, which is, of course, the 
most important ink used in printing, the ink being composed of the 
black pigment in a vehicle such as boiled linseed oil, other oils 
used according to requirements being perilla, tung and some mineral 
oils. The main desiderata are thus the pigment and the oil or 
varnish in which it is mixed. 

Printing inks are used in three main classes of work, viz. : 


1. Those for ordinary typographic work, 

2. Those for lithographic printing, 

3. Those for depressed surface printing, e.g., in copper-plate 
engraving work. 


The modern rotary printing-presses require an ink that will dry 
sufficiently rapidly to enable the presses to be operated at a high 
speed, that will flow freely, possess great covering power and make 
instantaneous and legible impressions.2° One lb. of carbon black 


mixed with 8 lbs. of oil and other materials will give sufficient ink 
. 55 


56 Blacks and Pitches 


to print 2,250 copies of a 16-page newspaper of ordinary size or 
90 copies of a 300-page octavo book. 

Certain carbon blacks give a “‘short”’ ink, 7.e., an ink of buttery 
consistency which does not flow rapidly, and such an ink is eminently 
suitable in lithographic and offset work, in slow-speed presses, and 
for most half-tones. Lampblack does not give the best consistency, 
and is too grey in colour. On the other hand, there are carbon 
blacks especially desirable where fast-running presses are in use, 
such blacks yielding a fluid “ long”’ ink, which has opacity enough 
to give a black letter. According to Underwood and Sullivan,® 
if a pigment mixed with a large quantity of oil remains stiff or cannot 
be drawn out into a string between the fingers, such pigment is said 
to be “ short,” and generally it happens that pigments showing this 
property are not suited to ink manufacture. On the other hand, 
an ink with a good flow and the property of being drawn out into a 
thread between the fingers is said to possess length, and the black 
which imparts these characteristics is said to be a “ long ”’ black. 

The properties of the various black pigments and their value 
as ink-making pigments have been ably summarised by Underwood 
and Sullivan ®° and are given in tabular form thus : 


TaBLE XIII. 
Properties of Blacks. 


Oil 


Name. Top hue. Under hue. absorption. Fineness. 

Bone black ...... Greenish-black | Brownish-black | Fairly low | Should be fairly 
fine, %.e., there 
should still be 
some grain 

Vine black ...... Greenish-black | Brownish-black | Fairly low — 

darker than 
bone black 

Carbon black ... Deep black Brownish-black High — 

Lampblack ...... Deep black Brownish-black High — 

Mineral black ... | Brownish-black | Decided brown ; Fairly low | Should be an im- 
palpable powder 

Magnetic pigment | Brownish-black | Decided brown Low 

Manganese black | Brownish-black | Decided brown Low 

Name. Flow. Shortness. Tastpers Atmospheric 
to light. influences. 

Bone black ...... Flows fairly well Fairly short No effect No effect 

Vine black ...... Flows fairly well Fairly long e is 

Carbon black ... Poor Short fe * 

Lampblack ...... Poor Short * . 

Mineral black ... Good Fairly long 5 a 

Magnetic pigment Good Long re re 


Manganese black Good Long 


Black Pigments for Ink Manufacture 57 
TaBLE XIII (continued). 


Abrasive 


Name. | Drying. Smoothness. qualities Incompatibility. 

Bone black ...... Exerts no Does not make Quite Mixes with 

drying action a smooth ink abrasive everything 

Vine black ...... a Does not make Quite es 

a smooth ink abrasive 

Carbon black ... | nes Works up very | Not abrasive ‘i 

smooth 

Lampblack ...... an Works up Not abrasive Ba 

smooth 

Mineral black ... . Does not make Quite = 

a smooth ink abrasive 

Magnetic pigment ve Works up Not abrasive oe 

very smooth 

Manganese black Fr: Works up Not abrasive Re. 

very smooth 
Name. Value as an Ink-making Pigment. 

Bone black ......... Of great value as a plate-printing ink material, although it must 
be mixed with vine black for colour and to give the proper working 
qualities. 

Vine black ......... Of great value as a toner to mix with bone black to give colour 
and working qualities to black plate-printing inks. 

Carbon black ...... The most important typographical black; in fact it is the base of 
all black typographical inks at the present day. 

Lampblack ......... | Not much used at present, as its place has been taken by the cheaper 


but similar carbon black. 
Mineral black ...... 
Magnetic pigment | +} Used principally to mix with other blacks. 
Manganese black . 


Such physical qualities and the methods of evaluating them as 
specific gravity, fineness, oil absorption, tinting strength and colour 
have already been discussed in the preceding chapter, and need 
not be dealt with again here, though in one way or another all have 
an interest to the ink-maker. 

Chemical tests have been dealt with in Chapter IV, and in con- 
nection with the amounts of volatile matter in blacks it may be 
mentioned that the halo sometimes to be observed round letters in 
some old books and papers has been attributed by Irvine 7° to the 
presence of tarry compounds such as chrysene, C,,H,, (m. p. 250°C.), 
and pyrene, C,,H,, (m. p. 148° C.), in the black used. Whilst there 
are no definite specifications laid down to which carbon blacks for 
ink-making must conform, the following have been suggested and 
are here re-printed from the Bulletin 2: 


Printing Ink. 


Chemical tests. Physical tests. 
Moisture ......... less than 5:0% COIOUE accvas must match standard. 
BBO pteccersst ces less than 0-1% Tinting 
Acetone extract . less than 0:1% strength . must equal standard. 


CSPI Vs voce ums enone wesiesetense none. 


58 Blacks and Pitches 


Practical Tests—The black when made into ink must have satis- 
factory working qualities as determined by an actual run on the 
press for which the ink is intended. The ink must have satisfactory 
transfer, tack, drying properties, colour, and must print a sufficient 
number of pages per pound. The oil must not separate from the 
pigment and there must be no offset or smutting. 

Testing Methods.—Chemical and physical tests are performed as 
previously described. Practical tests are to be made on the press 
for which the ink is intended. Specifications for tests to be made 
for which half-tone black ink is used are as follows : 


1. Non-separation of Oul from Pigment.—The oil or varnish should 
not separate from the pigment either on the face of the type or cuts 
or in the fountain, but should be short enough to break up readily 
in the distribution and not “ string.” 

2. Transfer.—In transferring from type or cuts to paper the ink 
should leave the face of the type or cuts reasonably clean. 

3. Hardness.—Ink should dry hard on the paper in 8 hours to 
admit of easy handling without damage or injury to the work, and 
should not pull the coating or the face from the paper, nor the face 
from the roller. 

4, Drying—Ink should not dry on the forme, rollers or distribu- 
tion, so that it may be easily removed therefrom. | 

5. Offset or Smutting.—The ink must be able to carry sufficient 
colour to print clean and sharp, without offset or smut on sheets 
_ falling on top from the pressfly or in piling the work. 

6. Colour.—The ink must dry a deep, solid carbon (not aniline) 
black, and not turn grey, nor have a metallic sheen or lustre, nor 
blister the face of the paper. 

7. Quantity Required.—The weight of the amount used must be 
noted and averaged on a basis of 5,000 printed pages. 


Methods to be used in making the Practical Tests.” 


1. The practical test of half-tone black ink shall be made on the 
flat-bed presses in use in the Government Printing Office. 

2. The test shall be made on coated book paper of the size, 
weight and quality in general use in the Government Printing 
Office. F 

3. The type or cut forme shall be previously “made ready ” and 
the press otherwise in good condition to make a satisfactory run. 

4. The forme, rollers, distribution, and ink fountain shall then 
be thoroughly washed and cleaned. The ink to be tested shall be 








Fic. 13.—Photomicrograph showing Agglomerated Particles 
of Short Carbon Black, 2 hrs. after preparation on the 
Slide. Magnified 500 diameters. 





Fic. 14.—Photomicrograph showing Dispersed Particles of 
Long Carbon Black, 2 hrs. after preparation on the Slide, 
Magnified 500 diameters. 


Black Pigments for Ink Manufacture 59 


weighed before being placed in the fountain. The quantity to be 
tested should be sufficient to run not less than 3 hours, and prefer- 
ably a run of 5 hours should be made. 

5. Ink that will separate the oil or varnish from the pigment 
on the face of the forme or in the fountain will not be accepted. 

6. To be satisfactory, ink, under the impression, should transfer 
from the face of the type or cuts to the paper, leaving the face of the 
type or cuts reasonably clean. It should be heavy in body, should 
feed well, and have sufficient “tack ’’ to dry on the paper rapidly 
enough, while printing, to avoid the necessity of using slip sheets; 
but it should dry hard on the paper in 8 hours, so that the work 
can be handled easily without damage or injury to the printing. 
It must not pull the face or coating from the paper and leave it on 
the forme or pull the face from the rollers. It should be removed 
easily from the forme, rollers and distribution, and must be able 
to carry sufficient colour without offset or smut, and print clean 
and sharp. 

7. The ink, to be satisfactory, must dry a deep, solid carbon 
(not aniline) black, and not turn grey, nor have a metallic sheen or 
lustre, nor blister the face of the paper. 


Photomicrographs of carbon black have been taken by Dr. 
Reinhardt Thiessen and are reproduced here by the courtesy of the 
U.S. Department of the Interior from Bulletin 192. Under the 
microscope, freshly-prepared mixtures of thin lithographic varnish 
with short and long black respectively at first appear precisely 
similar. They consist of ultra particles or of agglomerates of two 
_or three particles, but after a few minutes there is a progressive 
agglomeration of the particles to be noticed in the case of a “ short ”’ 
black and in about an hour there are groups with upwards of a 
hundred particles grouped together. In contrast, the “long ” 
black remains completely dispersed even after an interval of several 
hours. These differences are admirably illustrated in Figs. 13 
and 14. 

Long blacks are usually made with cylindrical burners and a 
cool flame, a method tending to the production of a black high in 
volatile matter, and it is suggested that these impurities prevent 
carbon particles from agglomerating. The tendency towards 
agglomeration is materially altered by the character of the vehicle 
in which the blacks are suspended. Lampblack shows the same 
tendency to agglomerate as do short carbon blacks, and this fact 
is borne out by the appearance in Fig. 15. As a rule, however, 


60 Blacks and Pitches 


lampblacks make long inks, so that the tendency to agglomerate 
does not account entirely for the difference in behaviour of different 
carbon blacks and of lampblack. 

Under the microscope lampblack and different grades of carbon 
black present much the same appearance. ‘There are differences in 
the amounts of coarse particles, but the different behaviour of 
the various blacks may be due to a difference in the constitution of 
the ultramicroscopic particles, possibly a difference in size, in 
attraction between the particles, and in surface energy at the oil- 
black interface, but the reliable data available hardly warrant the 
putting forward of even a tentative explanation of the different 
behaviour of “ long ”’ and “ short” blacks. 

Preliminary study of (1) viscosity, (2) cohesion, and (3) adhesion 
of mixtures of black pigment and oil has been entered upon, and in 
some measurements which have been made long blacks are shown 
to have lower cohesion than short blacks, which is what one would 
expect from their behaviour. It seems reasonable to surmise that 
the physical considerations will outweigh the purely chemical 
in any hypothesis which satisfactorily explains the behaviour of 
different blacks, not only as ink pigments, but as paint pigments 
too. 


REFERENCES. 


62 Analyst, 1922, 47, 9. ® De Architectura, lib. VII., 10.  ‘“‘ Inks, 
their Composition and Manufacture,” C. A. Mitchell and T. C. Hepworth, 
1916. 8° “The Chemistry and Technology of Printing Inks,” N. Underwood 
and J. V. Sullivan, 1915. 


Bibliography—Blacks as Ink Pigments. 


‘** Composition, Properties and Testing of Printing Inks,’”’ U.S. Bureau of 
Standards Circular 53, 1915. ‘‘ Carbon Black for Ink,”’ Gas Age, New York, 
1920, May 10th. ‘‘ Where the Printer Gets His Ink: America’s Carbon- 
black Industry,” Scientific American, New York, 1920, April 38rd. Thorpe, 
** Dictionary of Applied Chemistry,” Vol. ITI., 1922, p. 639. 





Fic. 15.—Photomicrograph showing Agglomerated Particles 
of Lampblack. Magnified 500 diameters. 





ub 





CHAPTER VIII 
CARBON BLACK AS A RUBBER PIGMENT 


Factors concerned in the Use of Compounding Ingredients in Rubber— 
Tests for Carbon Black in Rubber—Change in Elastic Constants— 
Stress—strain Relationships. 


Prior to the year 1914 carbon black and lampblack were used in 
the rubber industry only for colouring purposes, and to only a small 
extent. The presence of mineral ingredients in a fine state of sub- 
division in vulcanised rubber has long been recognised as capable of 
imparting desirable characteristics to such rubber, and a knowledge 
of the relative effects produced by different ingredients that may be 
used is of great importance.*® 

_ Zine oxide, which had early attained a position as an important 
filler for rubber, became too costly soon after the outbreak of the 
World War, and it was then shown that carbon black could be success- 
fully substituted as a filler in rubber. The favourable results 
achieved increased the use of carbon black enormously, and the 
present tendency is to manufacture black tread tyres instead of 
white ones.2° Since 1922 the demand from the rubber industry 
for carbon black has been so heavy that there has been a consequen- 
tial expansion in the production of carbon black from natural gas in 
the United States, the production in 1923 being an increase of 
104% over the production in 1922.°? 

Carbon black as a rubber pigment is now used to the extent 
of 3—20%, according to the purpose for which the rubber is 
required. On a volume basis, carbon black (sp. gr. 1-8) costs 
only one-third of the price of zinc oxide (sp. gr. 5-6, say), but 
actually in practice a greater volume of carbon black is used than 
of zinc oxide, so that the resulting mix with the black contains less 
rubber per unit volume than the zinc oxide mix. 

According to Greider,®® the principal factors governing the 
reinforcing effects of all compounding ingredients in rubber appear 
to be: 


1. Quantity of pigment or volume ratio pigment to rubber 
phase. 

2. Average particle size (specific surface). 

3. Wetting of pigment by rubber, or adhesion, surface 
tension. 

4. Flocculation of the pigment during incorporation or 
vulcanisation. 

5. Particle shape. 


6. Uniformity or size-frequency distribution. 
61 


62 Blacks and Pitches 


The influence of particle size on specific surface is of great 
importance in the rubber industry, and Wiegand,® in discussing 
the effect of surface area on the rubber stress-strain curve, gives the 
following figures : 

Apparent Surface. 


Barytes . . 30,480 sq. ins. per c. in. of pigment. 
Carbon Black . 1,905,000 _,, * “a 


The method of formation of carbon black is, of course, responsible 
for its fine state of subdivision and the corresponding enormous 
surface that ensues. Theoretically carbon black should be an ideal 
filler for rubber in virtue of its fine state of subdivision, because 
Ditmar 7° has found the following advantages accrue from the use 
of finely divided pigments in rubber mixtures : 


1. The nearly homogeneous mixing. 

2. The accelerated rate of cure. 

3. The reduction in cost by the increase possible in the per- 
centage of admixture. 

4, Increase in elasticity. 

5. The intensification of the colouring power. 

6. The smoother surface obtained, and greater resistance to 
abrasion. 

7. The longer life of the cured rubber. 


Now in all the above respects carbon black has been found to be 
an ideal rubber pigment, and it is claimed for it, in addition, that 
it protects rubber from the action of light and, furthermore, may 
even retard oxidation. 


The following tests have been suggested ? for use in testing carbon 
black for the rubber industry : 


TaBLE XIV. 
Carbon Black as a Filler for Rubber. 
Chemical tests. Physical tests. 

Moisture ......... less than 4% (rit cu duer a none (should com- 
Acetone extract. less than 0-5% pletely pass through 
At iipipieasaeen. less than 0:25% a 100-mesh sieve and 
7 feel as an impalpable 
powder when rubbed 

under the finger). 

Tinting 


strength . not less than 90% of the 
strength of standard. 


Carbon Black as a Rubber Pigment 63 


Practical Tests. 


Rubber mixes are made up containing equal weights of the 
sample to be tested and of the standard. Mixes are cured under 
exactly the same condition. The finished sheet is tested for tensile 
strength, per cent. elongation, toughness, and resistance to abrasion. 

Wiegand 71 and Schippel ** have investigated the volume increase 
of compounded rubber under strain, and also the stress-strain curves, 
and the results indicate generally that the finer the state of sub- 
division the larger the proportion of inert filler which can be mixed 
with rubber without resultant loss of tensile strength. In the case 
of carbon black, apparently up to 40% may be compounded, and 
the rubber is thus hardened and stiffened without loss of tensile 
strength. The volume increase at 200% elongation varies from 
1-46% in the case of carbon black and 1-76% in the case of lamp- 
black to 13-3°% in the case of barytes—azinc oxide apparently behaves 
somewhat abnormally. 


TABLE XV. 
The Results for Mixings containing 20 Volumes of Pigment 


Displace- Total Volume 
; Apparent ment of increase % 
Pigment. peice. stress-strain area at 200% 
curve. " | elongation. 
Carbon black ...... 1,905,000 42 640 1-46 
Lampblack ...... 1,524,000 4] 480 1-76 
Red oxide ......... 152,400 29 355 1-9 
Zinc oxide ......... 152,400 25 530 0:8 
bo) a 60,900 17 410 4-6 
Fossil flour ...... 50,800 14 365 3°5 
a are 30,480 8 360 13:3 


With the exception of zinc oxide, therefore, the increase in volume 
which occurs in compounded rubber when under strain is lowest 
when the particles are in the finest state of subdivision. The advan- 
tage of fine pigments relative to coarse ones is probably accounted 
for by the greater tendency of the compounded rubber, when 
stretched, to separate from the large particles.” 

The stress-strain curve for rubber reproduces in a simple manner 
the relation between the load and the elongation, and the displace- 
ment of the stress-strain curve refers to the increase in load sup- 
ported at a given elongation, and is thus a measure of the resistance 


64 Blacks and Pitches 


to stretching. In respect of this property the behaviour of carbon 
black and lampblack is in accordance with the size of their 
particles. 

W. W. Vogt and R. D. Evans ™ have investigated the stress— 
strain relationship and Poisson’s Ratio for all the common rubber 
compounding ingredients. For homogeneous isotropic substances 
the elastic constants and Poisson’s Ratio are the same in all direc- 
tions in the substance, but there are other substances where these 
constants and Poisson’s Ratio have different values, and such latter 
substances are termed anisotropic.’® As a result of their investiga- 
tions, these authors find the following fillers are isotropic, viz. : 
carbon black, lampblack, zinc oxide, barytes, lithopone, whilst the 
following are anisotropic, viz.: graphite, mica, magnesium car- 
bonate. It will be noted that graphite does not fall within the 
same category as carbon black and lampblack. 

Similar differences were noted by the authors in regard to volume 
increase under strain and permanent set; the permanent set was 
higher for mixtures with anisotropic fillers than for those with 
isotropic ones, and mixtures containing anisotropic fillers on tearing 
behave as though laminated. 

This anisotropy in properties is postulated as being due to the 
shape of the particles; particles with two dimensions notably 
greater than the third tend to align themselves during calendering 
with their longer axis in the direction of the calender, and their 
smaller dimension perpendicular to the plane of the calender. In 
consequence, different values for elastic constants and for Poisson’s 
Ratio are obtained for a compounded rubber, according as to 
which of three mutually perpendicular directions is chosen to make 
the test, 7.e., with the grain, across the grain, or vertical to the 
grain. 

The ultimate particles of lampblack and carbon black tend to 
approximate to the spherical shape from their very method of 
formation, and one would expect them therefore to be isotropic. 
The reader who is further inclined to pursue this study must consult 
some of the better-known works on rubber technology, to which 
domain the study properly belongs. 


REFERENCES. 


66 Indiarubber Journal, 1919, 58, 19. 67 See Appendix I, p. 171, 172. 
68 J. Ind. Eng. Chem., 1924, 16, 151. ®* Can. Chem. Journal, 1920, 4, 160. 
70 Chem. Zeitung, 1921, 45, 943. 71 J. Ind. Eng. Chem., 1921, 18,118. 7 Ibid., 
1920, 12, 33. 7% Annual Reports, Soc. Chem. Ind., 1919, 4, 324. 7 Vogt 
and Evans, J. Ind. Eng. Chem., 1923,15, 1015. 75 See Searle, «‘ Experimental 
Elasticity,’ Camb. Univ. Press, 


Carbon Black as a Rubber Pigment 65 


Rubber Pigments—Bibliography. 


Depew and Ruby, J. Ind. Eng. Chem., 1920, 12, 1156. Green, Journ. 
Franklin Inst., 1921, 192, 637. Green, J. Ind. Eng. Chem., 1921, 18, 1130. 
** Physics of Rubber,”’ Wiegand, ibid., 1922, 14, 854. ‘“‘ Fineness and Bulk 
of Pigments,’ Gardner, Circular 148, Paint Manufs. Assoc., U.S., 1922. 
** Determination of the Particle Size of Pigments,’? Vogt, Indiarubber World, 
1922, 66, 347. Luttringer, Caoutchouc et Gutta-Percha, 1922, 19, 11,308. 
Green, Chem. and Met. Hng., 1923, 28, 53. Greider, J. Ind. Eng. Chem., 
1923, 15, 504. ‘‘ Thermal Properties of Various Pigments and Rubber,” 
I. Williams, J. Ind. Eng. Chem., 1923, 15, 154-157. Weigel, U.S. Bureau 
of Mines, Technical Paper 296. Endres, J. Ind. Eng. Chem., 1924, 16, 1148. 
G. L. Cabot, Indiarubber Review, 1924, 24, Nov., p. 84. ‘* Determination of 
Distribution of Particle Size,’’ W. J. Kelly, Ind. Eng. Chem., 1924, 16, 928. 
Indiarubber Review, 1923, 28, 754. 


CHAPTER IX 
PITCHES AND BITUMINOUS MATERIALS 


Introduction—Factors Involved in Classification—Definitions—Complete 
Classification. 


Introduction and Classification 


On various parts of the earth’s surface, notably in Syria, Egypt, 
Trinidad, Bermudez, California and Utah, occur mineral deposits, 
some of which are hard, brittle and black, whilst others are soft 
and viscous, black fluid masses. Allied to these in respect of many 
of their properties, and notably as regards applicability, are those 
black residues which arise out of the distillation, frequently 
destructive, of such familiar substances in the organic world as 
coal, wood, peat, petroleum, bone, fatty acids and greases. ‘The 
terms Pitch, Asphalt, Asphaltum, Bitumen are variously and some- 
what indiscriminately applied to these natural and manufactured 
products, and in consequence a certain confusion arises at times. 

Many of these natural deposits have been known in the East 
from time immemorial, where their first use appears to have been 
in the nature of a cement for joining objects together. The 
word asphalt is traceable to Babylonian times, to the Greek 
aéodadroc, through late Latin asphaltum to the French asphalte 
and ultimately the English asphalt. (Milton, Paradise Lost, i, 729, 
refers to “asphaltus’’?). The term bitumen originated in 
Sanskrit. 

The earliest recorded use of asphalt by the human race goes 
back to the Sumerians, who were the pre-Babylonian 7° inhabitants 
of the Euphrates valley. 1t was also known to the early Persians 
and to the ancient Egyptians, who used it in connection with their 
burial rites.77 In the Old Testament there is reference to it in 
connection with the Tower of Babel (circa 2000 B.c.) and in con- 
nection with incidents relative to the infancy of Moses (circa 
1500 B.c.).78 

From its earliest mention in the literature of Greece, Rome and 
Palestine, the typical asphalt of commerce was the solid bitumen, 
found on the shores of the Dead Sea, of the following proximate 
composition 7° : 


Carbon : . Tie 
Hydrogen . ; . ae 
Oxygen : , ; . dey, 
Nitrogen. : : : a ot fy = 


and closely analogous is the Egyptian bitumen : 
66 


Pitches and Bituminous Materials 67 


Carbon s . ; j 1 8h38% 
Hydrogen . ; fag eenB2%, 
Oxygen é A ; ; - 56-26% 
Nitrogen. ; ; : 5 QE 


According to Nebuchadnezzar, his father Nabopolassar (625— 
604 B.c.) laid the first asphalt block pavement of which any record 
is extant.°° Hannibal of Carthage (250 B.c.) used asphalt in war- 
fare, and Pliny the Elder of Rome about a.p. 100 makes reference 
to asphalt, which, he says, must be glossy and black. 

Asphalt was discovered in Cuba ® in 1535, and the Pitch Lake in 
Trinidad ®° by Sir Walter Raleigh in 1595. In 1661 we find refer- 
ence to the production of wood tar on the large scale by the dry 
distillation of wood, and later, in 1681, the discovery of coal tar 
pitch was made in England, a patent relative thereto being taken 
out by Becher and Serle. *° 

During the nineteenth century many advances were chronicled 
in connection with our knowledge of asphaltic and pitch-like sub- 
stances, and the first use of the asphalt pavement is to be recorded 
in London, Paris and the large cities of U.S.A. Such natural 
bitumens as gilsonite were discovered in Utah in 1885, and the 
same century saw the manufacture and use of stearine pitch and 
petroleum pitch—residues of the distillation of fatty acids and 
petroleum respectively. | 

As already mentioned, owing to the loose and indiscriminate 
way in which the terms “ bitumen,” “tar,” “ pitch,” “ asphalt,” 
etc., have been used for centuries, coupled with the fact that the 
physical properties and the chemical composition of the substances 
so designated were little understood, the problem of accurately 
defining and systematically classifying the various pitches and 
bituminous substances has proved extraordinarily baffling. At 
the present time there is no uniform or accepted standard of nomen- 
clature, though much has been done towards evolving order out of 
chaos by the work of Abraham,*! Clifford Richardson *? and the 
British Engineering Standards Association.*? In his recently 
published book, P. E. Spielmann **« has reviewed at some length 
and somewhat chronologically the various attempts that have been 
made to secure uniformity of definition and nomenclature of 
- Bituminous Substances. The present author ®* in an earlier 
publication used the term bitumen to define a class of substances, 
not necessarily solid, occurring in nature, and which are soluble 
in carbon disulphide, chloroform and other neutral liquids, and 
consisting essentially of compounds of carbon and hydrogen asso- 


68 Blacks and Pitches 


ciated frequently with compounds of oxygen, sulphur and nitrogen 
with possibly traces of mineral matter, the latter consisting of 
compounds of iron and alumina. Adopting this definition, one 
would then. regard the asphalts as mineral matters containing 
bitumen in intimate association. Richardson has suggested the 
term “residual pitches ” for those closely allied artificial products 
arising during the distillation of organic bodies. 

Broadly speaking, the foregoing is in substantial agreement 
as regards its main outlines with the more elaborate and detailed 
system of definition and classification adopted by Abraham,*® 
and the present author has adopted in this volume the system of 
Abraham, except in respect of certain substances which have 
been omitted from that writer’s scheme for reasons which will be 
indicated later. 

The following criteria, viz., origin, physical properties, solubility 
and chemical composition, form the basis for a preliminary classi- 
fication indicated in the accompanying table : 


TABLE XVI ® 


Mineral 
Native | Veuotable 
is Animal 
Origin Evaporation (fractional distillation) 
Destructive distillation 
Pyrogenous {eae in a closed vessel 
Blowing with air 
Colour in Light (white, yellow or brown) 
mass Dark (black) 
Liquid 
Consistency | Viscous 
or hardness | Semi-solid 
Solid 
Conchoidal 
Fracture Hackly ‘ 
Waxy 
Physical Lustre | Resinous 
properties Dull 
Adherent 
Feel | Non-adherent 
Unctuous (waxy) 
Oily (petroleum-like) 
Odour Tarry 
Volatility Non aclatile 
Fusible 
Fusibility {Difieuiy fusible 
Infusible (melts only with decomposition) 
Non-mineral constituents in carbon disulphide 
Solubility {Distillate at 300 to 350° C. in sulphuric acid (¢.e. “‘ sulphona- 
tion residue ’’) 
Hydrocarbons (compounds containing carbon and hydrogen) 
feet bo hanes ee (compounds containing carbon hydrogen 
Ne and oxygen 
eS ie ihe Grvptallinabic paraffins (crystallise at low temperatures) 
Mineral matter (inorganic substances) 








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op TAX Wavy, 


70 Blacks and Pitches 


In Table XVII the most important types of bituminous sub- 
stances and pitches are classified according to the features 
enumerated in Table XVI. Abraham, in his system of classifica- 
tion, has included the Mineral Waxes amongst the bituminous 
substances, but since these waxes, such as ozokerite and montan 
wax, are so closely akin to paraffin wax, at any rate in general 
physical properties and to a considerable extent in chemical com- 
position, it appears preferable to exclude these waxes from the 
scheme of classification. Furthermore, the present author does not 
deem it advisable to include, as Abraham does, Petroleum. It 
appears better to consider petroleum as the parent substance of 
certain bitumens rather than as a species of bitumen itself, and 
there is ample evidence to support this preference, and consequently 
petroleum is not included in Table XVIII. 

The definitions which follow are taken from Abraham’s classi- 
fication,®® and they help to a clear understanding of Table XVII 
and to that of Table XVIII, which follows in further elaboration. 

Bitumen.—A term applied to native substances of variable 
colour, hardness and volatility; composed of hydrocarbons and 
substantially free from oxygenated bodies; sometimes in associa- 
tion with mineral matter, the non-mineral constituents being 
fusible and largely soluble in carbon disulphide; and whose 
distillate, fractionated between 300° and 350° C., yields considerable 
sulphonation residue. 

This definition includes petroleum and native mineral waxes, 
which the author, however, prefers not to include in any system 
of classification of bitumens. 

Pyrobitumen.—A term applied to native substances of dark 
colour, the word “ pyrobitumen ”’ implying that the substances, 
when subjected to heat, will give rise to bodies resembling bitumens 
in their solubility and physical properties. They are comparatively 
hard and non-volatile; composed of hydrocarbons, which may or 
may not contain oxygenated bodies; sometimes associated with 
mineral matter, the non-mineral constituents being infusible and 
relatively insoluble in carbon disulphide. 

Asphalt.—A term applied to a species of bitumen and also to 
certain pyrogenous substances of dark colour, of variable hardness, 
comparatively non-volatile ; composed of hydrocarbons, substantially 
free from oxygenated bodies; containing relatively little or no 
crystallisable paraffins; sometimes in association with mineral 
matter, the non-mineral constituents being fusible, and largely 
soluble in carbon disulphide; and whose distillate, fractionated 


Pitches and Bituminous Materials 71 


between 300° and 350° C., yields considerable sulphonation 
residue. | 

_ Asphaltite—A species of bitumen, including dark-coloured, com- 
paratively hard and non-volatile solids; composed of hydrocarbons, 
substantially free from oxygenated bodies and crystallisable 
paraffins; sometimes associated with mineral matter, the non- 
mineral constituents being difficultly fusible, and largely soluble in 
carbon disulphide, and whose distillate, fractionated between 300° 
and 350° C., yields considerable sulphonation residue. 

Asphaltic Pyrobitumen.—A species of pyrobitumen including 
dark-coloured, comparatively hard and non-volatile solids; com- 
posed of hydrocarbons, substantially free from oxygenated bodies; 
sometimes associated with mineral matter, the non-mineral con- 
stituents being infusible and largely insoluble in carbon disulphide. 

Non-asphaltic Pyrobitumen.—A species of pyrobitumen, includ- 
ing dark-coloured, comparatively hard and non-volatile solids; 
composed of hydrocarbons, containing oxygenated bodies; some- 
times associated with mineral matter, the non-mineral constituents 
being infusible and largely insoluble in carbon disulphide. 

Tar.—A term applied to pyrogenous distillates of dark colour, 
liquid consistency, having a characteristic odour; comparatively 
volatile; of variable composition; sometimes associated with 
carbonaceous matter, the non-carbonaceous constituents being 
largely soluble in carbon disulphide, and whose distillate, frac- 
tionated between 300° and 350° C., yields comparatively little 
sulphonation residue. 

_ Pitch.—A term applied to pyrogenous residues, of dark colour, 
viscous to solid consistency; comparatively non-volatile, fusible; 
of variable composition; sometimes associated with carbonaceous 
matter, the non-carbonaceous constituents being largely soluble in 
carbon disulphide, and whose distillate, fractionated between 300° 
and 350° C., yields comparatively little sulphonation residue. 


The preceding definitions allow construction of the detailed 
classification in Table XVIII. This latter agrees with that of 
Abraham, except that petroleum and native mineral waxes have 
not been included, whilst the non-asphaltic members (peat, lignite, 
coal and their shales) have been omitted, as likewise also have 
the pyrogenous waxes, though included by Abraham. The present 
author considers all such substances quite outside such a classi- 
fication. 


Blacks and Pitches 


72 


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73 


Pitches and Bituminous Materials 





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74 Blacks and Pitches 


REFERENCES. 


76 “ Civilisation of Babylonia and Assyria,” Morris Jastrow, jun., Phila- 
delphia, 1915. 7? ‘‘ Memoires-Délégations en Perse,’ ed. by J. de Morgan, 
Vol. XITI., Paris, 1912. 78 Genesis xi. 3 and Exodus ii. 3. 79 Thorpe, 
‘** Dictionary of Applied Chemistry.” 8 ‘‘ Asphalts and Allied Substances,” 
Herbert Abraham, New York, 1918, Chaps. land II. 8! “ The Classification 
of Bituminous and Resinous Substances,” by H. Abraham, J. Ind. Eng. 
Chem., 1913, 5, 11. ® ‘‘The Modern Asphalt Pavement,” by Clifford 
Richardson, New York, 1908. 8 ‘‘ British Standard Nomenclature of 
Tars, Pitches, Bitumens, and Asphalts, when used for Road Purposes,” 
London, April, 1916. 8 ‘‘ Bituminous Substances,”’ by Percy E. Spielmann, 
1925, Ernest Benn, Ltd. §®4 H. M. Langton, Journ. Ow and Colour Chem. 
Assoc., 1919, 2, No. 7. 


Pitches and Bituminous Substances—Bibliography. 


** Asphalts and Allied Substances,”’ by Herbert Abraham, D. Van Nostrand 
Company, New York, 1918. ‘‘ Trinidad and Bermudez Lake -Asphalts,”’ 
Barber Asphalt Paving Company, Philadelphia. ‘‘ Asphalts,” by T. H. 
Boorman, New York, 1908. U.S. Department of Agriculture, Office of 
Public Roads, Circular No. 93, 1911. Proc. American Society for Testing 
Materials, 1916, 16, Part I, 594. ‘‘ Bituminous Substances,” by Perey E. 
Spielmann, Ernest Benn, Ltd., London, 1925. 


CHAPTER X 
THE CHEMISTRY OF THE BITUMENS AND PITCHES 


Paraffinoid, Aromatic and Naphthenic Hydrocarbons—Nitrogenous, Oxy- 
genated and Sulphur Compounds. 


THE bitumens and pyrobitumens occurring in nature as well as the 
somewhat related manufactured pitches are complex mixtures of 
chemical compounds containing the elements carbon and hydrogen— 
the Hydrocarbons—in varying proportions and combined in a 
variety of ways. Some of the compounds may contain the elements 
oxygen, sulphur and nitrogen, and smaller or larger amounts of 
extraneous mineral matter are usually found in intimate associa- 
tion. Hydrocarbons occur in all types of bituminous substances— 
_ in fact, they predominate—and they are briefly considered below : 
Hydrocarbons.—The following series are known to occur : 


C, Hons. Sertes—Paraffins. 


| Name. Formula. M.p.(°C.). B. p. (°C.). 
Liquid : ) 
Pentane CHio — +38 
Hexane Cea, _ +69 
Heptane CH. - +98 
Heptadecane C,,H3¢6 22 —- 
Solid : 
Octodecane C,,H3¢ 28 317 
Nonadecane CoHs0 32 330 
Eicosane Cop Has 37 205 
at 15 mm. 

Dimyricyl Coo Hi00 102 -- 


The liquid members and their isomers are associated together in 
such petroleums as that of Pennsylvania and in certain asphalts, 
whilst some of the solid members occur in low-temperature tars 
from coal. . 


C,H., Series—Olefines (one double bond). 


Name. Formula. M.p.(°C.). B.p.(°C.) 
Inquid : 

_ Amylene and isomers CH —— +-39 
Hexylene oi C,H. — 69 
Heptylene C,H,, — 95 
Kikosylene ) Cap Ha — 314 

Solid : 
Cerotene Cy,Hs4 +58 


Melene C5oH 69 +62 375 
75 


76 Blacks and Pitches 


These and their isomers are present in some American petroleums 
in small amount. 


C,H» Series—Acetylenes (one triple bond). 


Name. Formula. Bepo(tas: 
LInquid : 
Crotonylene C,H, 27 
Isopropylacetylene C;H, — 


Several of the higher members are found in Texas, Louisiana 
and Ohio petroleums and in coal tar, 


C, Hon» Series—Diolefines (two double bonds). 


Name. Formula. Bop G3: 
Allylene (Propadiéne) CH,-.C:CH, Gas 
Divinyl (Erythrene) CH,:CH-CH:CH, 5 
Piperylene («-Methylbutadiéne) CH,:CH*CH:CH-CH, +42 
Isoprene (8-Methylbutadiéne) CH,-CH:-C(CH;):CH, +35 
Conylene CH,:CH-CH,CH:CH-CH,CH,CH, 126 


These hydrocarbons occur in tars and in certain petroleums. 


CrH2,-4 Serves—Olefinacetylenes. 


Some of these occur in certain types of Californian petroleum. 


C,H., Series—Naphthenes or Cycloparaffins or Polymethylenes. 


Name. Formula. M: p. OC). Bopp iae: 
Cyclopropane (Trimethylene) CH<te —126 —35 
Cyclohexane (Hexamethylene) oe +6 81 
Cyclononane (Nonomethylene) CH,- CH, CH, Clon: 171 


CH,—CH,—CH,—CH, 


These occur in American mixed-base and asphaltic petroleums 
(including Ohio, Californian and Canadian) and in fatty acid 
pitches. 


C,H2,-2 Series—Polycylic Polymethylenes. 


These are usually associated with members of the previous 
series. 


The Chemistry of the Bitumens and Pitches ja 


C,H», Series—Cyclo-olefines (one double bond). 


H 


These include cyclo-ethylene, Oa ee, 


CH—CH 
propylene, C,H,,.< jee 
y 5“ °CH,—OH,—CH, 
They occur in Texas oils and in certain asphalts. 


panne’ | 
, and cyclo- 
s—CH, z 


C,H», Series—Monocyclic Benzenes. 


Name. Formula. Bop. C0. 
as 
Benzene C,H, or L | 80 
é * 
_ Toluene or Monomethylbenzene C,H,:CH, or | hack > 110 
Xylenes C,H,(CH3). 
CH, CH, CH 
\ 
or Dimethylbenzenes | as Clon ( 
eee Ae are etl 
CH, 
ortho- meta- para- 
b. p. 142°. b. p. 139% b. p. 138°. 
Trimethylbenzenes (3) C,H.(CH3)s 
Hexamethylbenzene C,(CHs)¢ 305 


Members of this series and their respective isomers are present 
in coal tars, water gas tar and other pyrogenous distillates. Traces 
have been found in many petroleums and in lignite tar. 


C,H en-g to C,Hn-39 Sertes—Monocyclic and Polycylic. 

C,,H,,- 3 Serves, of which the principal member is phenylethylene, 
C,H;°CH:CH,. 

C,H,;-1. Sertes—the Indenes, of which the principal members 
are indene, C,H,°C,H., b. p. 182° C., hydrindene, C,)H,49, b. p. 176° C., 
and the methylindenes and dimethylindenes. 

Cr, Hon-1, Sertes—the Naphthalenes, the principal member of 


Se Lars Ks 
which is naphthalene, C,,H,, represented thus : © | ; 
fe 


C,Hon-14 Series—the Diphenyls, the principal member of which 


is diphenyl, C,,H,,, represented as Gas Rais: The next member 


of the series is methyl diphenyl, C,,H,°CH3. 


78 Blacks and Pitches 
C,Hen-14 Series—the Acenaphihenes, the first member of which 


FG Was 2) 
is acenaphthene, C,.H,), which is represented as Ms ih age ee 
H,C—CH, 

CrHon-1, Series—the Diphenylenes, which include fluorene, 


C,H 
C,3H,5, represented as fe “NOH, or \Z SCH, ; stilbene, 


C,H,*CH:CH:C,H,. 
C fe tS potas 8s Anthracenes, of which the chief niger 


vA ny ree 
are anthracene, C,,H,,, represented as | |... dea, Shae 
\A ON 


P< y 
phenanthrene, C,,H,, represented as \/ Wa wae b. p. 340° C.; 
( \CHs / 


retene, C,,H,5; oe ib. p. 3507 CG. 


Pay 
ee 
C3H, 
C,Hon-29 Serves—principal member fluoranthene, C,;H jo. 
C,Hon-22 Sertes—principal member pyrene, C,H 4. 
ntLon-24 Sertes—principal member chrysene, C,gH4o. 
The hydrocarbons of all the foregoing series, C,H,,-, to 
C,,Hon-39, all occur in coal tar and the higher members of many 


ie a ¥e ~ 
of the series in coal-tar pitch. Indene, | _ vn C,H,'°C,H,, 
i , 


CH, 
and styrene, C,H ;*CH‘CHg, have been identified, and their respective 
amounts present determined by R. L. Brown and R. D. Howard ® 
recently in samples of water-gas tar, whilst J. M. Weiss and C. R. 
Downs *° have isolated 4% of phenanthrene, C,,H,), and 0:1% 
of diphenyl, (C,H;)., from coke-oven tar. 


Oxygen-containing Compounds. 


Water occurs in small quantities in most native asphalts, in 
crude tars and to some extent in pitches. 


- 


The Chenustry of the Bitumens and Pitches 


Alcohols : 


Methy] Alcohol, CH,-OH. 
Ethyl Alcohol, C,H,-OH. 


Cetyl Alcohol, C,H3°OH, b. p. 344° C. 
Ceryl Alcohol, C,,H;,-OH, m. p. 79° C. 
Myricyl Alcohol, C,,H,,;-OH, m. p. 88° C. 


79 


The higher waxy members of this series are present in wool 


wax or grease and in wool grease pitch and in certain bitumens. 


Ketones : 


Acetone, CH,°CO:CH;, and its higher homologues are found in 


wood tar and certain lignite and blast-furnace tars. 


Phenols : 
Phenol, C,H;OH, b. p. 182-6° C. 
Cresol or Methyl Phenol (3 isomers), CH,°C,H,-OH. 
Dihydric Phenols (3 isomers), C,H,(OH),. 
Guaiacol, OH:C,H,-OCHs. 
Trihydric Phenols, C,H,(OH)s. 


These and higher homologues and derived esters are found in 
coal tar and lignite tar, whilst guaiacol and other esters of the 
cresols and the trihydric phenols are found in wood tar and wood- 


tar pitch. 


Fatty Acids : . 
C,,H,,0, Series : 


Acetic Acid, CH,-COOH, b. p 137-9° C. 


Lauric Acid, C,,H,,-COOH, m. p. 43-6° C. 
Myristic Acid, C,,H,,-COOH, m. p. 53-8° C. 
Palmitic Acid, C,;H,,-COOH, m. p. 62:6° C. 
Daturic Acid, C,,H;,;>COOH, m. p. 59-5° C. 
Stearic Acid, C,,H;,;-COOH, m. p. 69-3° C. 
Arachidic Acid, C,,H,,,;>COOH, m. p. 77° C. 
Behenic Acid, C,,H,,;COOH, m. p. 83:8° C. 
Lignoceric Acid, C,,H,,,;COOH, m. p. 80-:5° C. 
Cerotic Acid, C,,H;,,;COOH, m. p. 77-8° C. 
Montanic Acid, C,,H;,-COOH, m. p. 83° C. 
Mellisic Acid, C,,Hz9*COOH, m. p. 91° C. 


Acetic acid is present in wood tars, whilst the higher members 


80 Blacks and Pitches 


of this series from palmitic acid upwards, together with their corre- 
sponding lactones and esters, are found in fatty acid pitches, and 
the members from cerotic acid upwards in wool grease pitch and 
in certain bitumens. 


C,Ho,-20. Series : 
Amongst the higher members are 


Oleic Acid 
Elaidic Acid fC17Hlse' COOH 
Erucic Acid, C,,H,,;COOH 


Some of the higher members of this series are found in fatty 
acid pitches. : 

Resin Acids.—These are of somewhat uncertain structure, but 
the abietic acids and their homologues containing a phenanthrene 
or retene hydrocarbon structure are known to occur in rosin oil, 
and are probably present, together with their esters, anhydrides 
and lactones, in wood tars, especially pine tar, in pine pitch and in 
resin pitch. Various constitutions of the type represented by 
Griin, viz., 

CH, 
COOH-C/ \c(CH,), 
CH 


Hol Ac 


ae 
Boe 
CH 
HC ey 


CH, 


Cy Hs.02, have been attributed to abietic acid, but at present the 
constitution of this and of allied resin acids is undecided, though 
an able summary of our present knowledge has been contributed 
by C. E. Soane.’? 

A number of highly complex resinous and oxygenated com- 
pounds are found in many of the soft naturally occurring asphalts, 
but their complete separation and identification have not yet been 
achieved. 


Sulphur Compounds : 
Carbon_Disulphide, CS,, b. p. 46-5° C. 


Thiophene, C,H,8, represented as ul 2 b. p. 84° C. 
S 


The Chemistry of the Bitumens and Pitches 81 


a-Thiotolene, CH,°C,H,'S or \, ) On pits DOELZS 0 
Oe 
B-Thiotolene, CH;°C,H,'S or x A ep. bie. 


Thioxenes and their isomers, sees 
Methyl Sulphide, (CH,),8, b. p. 37-5° C. 
Ethyl Sulphide, (C,H,),S, b. p. 92° C. 
Methyl Mercaptan, CH,-SH, b. p. 6° C. 
Ethyl Mercaptan, C,H,;SH, b. p. 36-2° C. 


Some or all of the above compounds are known to occur in 
certain petroleums, their derived asphalts, in certain pyrobitumens, 
notably in coal tar and lignite tar, and probably in the corresponding 
pitches. 


Nitrogenous Compounds : 
Aniline, C,H;NH,, b. p. 183° C. 
fos 
Pyridene, C,;H;N, represented as a yp b. plo C. 


Picolines or Methyl Pyridines (3 isomers), CH,°C,H,N. 
Lutidines or Dimethyl Pyridines (4 isomers), (OH, }e C, HN. 
Collidines or Trimethyl Pyridines, (CH,),°C;H,N. 
NH 
Indol, C,H,N, represented as aid ‘ 
N 

A: a _ 
& is 


Isoquinoline, C,H,N, represented as Seve o and their 
NS 


f 


Quinoline, C,H,N; represented as 


homologues. 
N 
Acridine, C,,;H,N, represented as ‘ be Se: 
ER Re NS 
Pyrrol, C,H;N, represented as es , b. p. 180—131° C. 
NH 
Carbazol, C,,H,N, b. p. 238° C. 


Very small amounts of some of the foregoing are found in 


82 Blacks and Pitches 


fatty acid pitches, though all are present in coal tar; some are 
present in petroleum asphalts and lignite tar and the less volatile 
in coal-tar pitch and lignite-tar pitch. 

It is evident that the chemistry of bituminous substances and 
pitches is very complicated in view of the fact that their com- 
position is not definite, but consists of mixtures of numerous 
chemical compounds in varying amounts. No single bitumen or 
pitch has been completely separated into its constituent compounds, 
though, of course, the composition of coal tar is to a great extent 
known. 

According to Abraham,* the element nitrogen is rarely present 
in excess of 2% of the non-mineral constituents of a bituminous 
substance. Asphalt, asphaltites and pyrobitumens contain varying 
amounts, up to a maximum of about 1-7%, of nitrogen, and tars 
and pitches, except fatty acid pitches, may contain up to 1% of 
nitrogen. 

The amount of sulphur in bituminous wieieape such as native 
asphalts, asphaltites and asphaltic pyrobitumens may vary from 
0 to 10%, but sulphur compounds are practically absent from all 
the pyrogenous pitches, 7.e., those from wood tar, fatty acids, 
coal tar. 

According to the investigations of O. C. Ralston,®® the per- 
centages of carbon, hydrogen and oxygen in bituminous compounds 
appear to follow some well-defined laws. 

For fuller information on the chemical structure, properties, 
reactions and physical constants and general characters of the 
various hydrocarbons, oxygen-containing, nitrogenous and sulphur 
compounds mentioned in this chapter, the reader is referred to any 
of the well-known standard text-books of organic chemistry. 


REFERENCES. 


85 Industrial and Eng. Chem., 1923, 15, 1147. 8° Ibid., 1923, 15, 1022. 
8? Journ. Oil and Colour Chem. Assoc., 1922, 5, No. 35 (cf. Volume on Resins 
in this series). §8* Technical Paper No. 93, U.S. Dept. of the Interior, Bureau 
of Mines, 1915. 


CHAPTER XI 


METHODS OF TESTING BITUMINOUS MATERIALS 
AND PITCHES 


American and British Standardisation—Physical, Heat, Solubility and 
Chemical Tests and their Uses. 


THE tests which an investigator will apply to any given material 
may serve as a means of identification, as a criterion of purity, 
as an aid to manufacturing control or as an indication of the use 
to which the material may be applied. In this last-named con- 
nection, many of the tests to be applied to a bituminous material 
or pitch will depend on whether the material is to be used in manu- 
facturing a bituminous varnish or a japan, in preparing a water- 
proofing material for a damp course or in highway construction. 
| The standardisation of testing of asphalts, solid and semi-solid 
bitumens, tars and pitches was undertaken in the United States 
a very considerable time ago by the American Society for Testing 
Materials (A.S.T.M.) and very valuable work was achieved. More 
recently in this country, thanks to the pioneer work of the Insti- 
tution of Petroleum Technologists, the task of fixing standard 
tests for Petroleum and its various products has been started and 
considerable progress has been made. The work of the committee 
engaged on the task has been reported upon by A. E. Dunstan.* 
Many of the standard tests of the A.S.T.M. have been recommended 
for use by this British Committee, who have, however, deferred 
their decision in the case of many of the tests pending further 
reports from sub-committees. 

The present author in this volume has adopted the tests and 
the numbers attached thereto as given by Herbert Abraham *° in 
his volume on “ Asphalts and Allied Substances,” and the reasons 
that have prompted this course are that many of the tests given 
are already the adopted standards of the A.S.T.M., and are recom- 
mended by the British Committee already referred to. Further- 
more, Abraham’s scheme of testing is very full and embraces tests 
adequate for all the industries concerned in the use of bituminous 
materials and pitches. 3 

In the following pages most of the tests are given only in bare 
outline, as considerations of space forbid any other treatment, but 
full description of tests with illustrations of apparatus to be used 
are given by Spielmann.®** Moreover, it is not the purpose of the 
present volume to give detailed descriptions of apparatus and 
technique largely described in the well-known standard works on 
Chemical Analysis and Experimental Physics. 

83 


84 Blacks and Pitches 
TABLE XIX. 
Tests to be Applied to Bituminous Substances. 
Test No. Description. Test No. Description. 
Physical characteristics : Solubility tests : 
Test 1 | Colour in mass Test 21 | Solubility in carbon di- 
Test 2 | Homogeneity sulphide 
Test 3 | Appearance of surface aged | Test 22 | Carbenes 
one week Test 23 | Solubility in 88° petroleum 
Test 4 | Fracture naphtha 
Test 5 | Lustre Test 24 | Solubility in other solvents 
Test 6 | Streak on porcelain UE eane cee Mn 
Test 7 | Specific gravity Chemical testa + 
Test 8 | Viscosity Test 25 | Wat : " 
Test 9 | Hardness or consistency Test 96 | 0 prying 
Test 9dj| Susceptibility factor Tes 9 uv, oe 
Test 10 | Ductility ont FF ydrogen 
. Test 28 | Sulphur 
Test 11 | Tensile strength Test 29 | Ni Hi 
Test 12 | Adhesiveness Tea es ee 
est 30 | Oxygen 
See eas Test 31 | Free carbon in tars 
Heat tests : Test 32 | Naphthalene in tars x 
Test 13 | Odour on heating Test 33 | Solid paraffins 
Test 14 | Subjection to heat Test 34 | Saturated hydrocarbons 
Test 15 | Fusing point Test 35 | Sulphonation residue 
Test 16 | Volatile matter Test 36 | Mineral matter 
Test 17 | Flash point Test 37 | Saponifiable constituents 
Test 18 | Burning point Test 38 | Asphaltic constituents 
Test 19 | Fixed carbon Test 39 | Unsaponifiable matter 
Test 20 | Distillation test Test 40 | Glycerol 
Test 41 | Diazo reaction 
Test 42 | Anthraquinone reaction 
Test 43 | Liebermann-Storch 
reaction 
Test 44 | Iodine number 





Test 1.—This test calls for no comment, though it is of some 
use as a means of identification. 
Test 2.—Homogeneity of the Material to the unaided Eye 


at a temperature of 77° F., or when surveyed under the microscope 
or when melted, are aids to establishing the identity of the material 
under examination, and serve to show the presence or absence of 
mineral matter and free carbon. 

Test 3.—Appearance of Surface Aged one Week. A small 
quantity of the bituminous material melted at the lowest possible 
temperature is, after examination of its surface, covered for a 
week, to protect it from dust, and then re-examined. If bright 
and lustrous it will indicate perfect amalgamation of constituents 
and absence of oily and undissolved constituents—a lustreless 
surface indicates the contrary. 


Methods of Testing Bituminous Materials and Pitches 85 


Test 4.—Fracture may be conchoidal (rounded and curved like 
a shell), or hackly (irregular and rough), and only hard and brittle 
substances yield to this test. 

Test 5.—Lustre serves as a means of identification—it gives 
indications of the presence or absence of waxy, greasy constituents. 

Test 6.—Streak on Porcelain. This represents the colour of the 
powder left behind on drawing a piece of the bituminous material 
across the surface of unglazed porcelain, and the test serves to 
indicate the use of the material with coloured pigments. 

Test 7.—Specific Gravity. This test serves as a means of 
identification and of figuring the weight of a given volume of the 
material under test. The test is ascertained by the usual hydro- 
meter, Westphal balance and specific gravity bottle methods, the 
exact instrument to be used with a given material being conditioned 
by its nature and consistency. In this country the standard 
temperature is 15-5° C. (60° F.) but the A.S.T.M. adopt 77° F. 

Test 8.—Viscosity. This test is of use in the examination of 
materials for road construction. The Engler, Redwood, Saybolt 
viscosimeters are used in connection with this test, the main use 
of which is in the examination of liquid and semi-liquid substances 
for road purposes. The use of these instruments is fully described 
by B. Redwood, J. Lewkowitsch 1 and others. 

For testing the viscosity or consistency of semi-solid bituminous 
materials for road purposes the Float Test (Test 8d) is adopted, 
and this test is not vitiated by the presence of mineral matter or 
free carbon. 

The instrument as described by Abraham consists of an 
aluminium saucer-shaped float and a conical brass collar weighing 
exactly 50 grams together.’ The brass collar is fitted with melted 
bituminous material upon placing it against a brass plate, the 
surface of which has been amalgamated with mercury. After 
cooling it is levelled, placed in water at 41° F. for 15—30 minutes 
along with the aluminium float, and then screwed into the float 
and immediately floated on the surface of water warmed to a desired 
temperature, with the brass collar downward. Very soft materials 
are tested at 32° F. and hard bituminous substances at 122° or 
150° F. As the heat is transmitted through the brass collar into 
the plug of bituminous material, the latter softens until it is forced 
upwards and out of the collar by the weight of the instrument. 
The time elapsing between the placing of the float on the surface 
of the water, and when the water breaks through the plug, is taken 
as a measure of the viscosity of the material under test. 


86 Blacks and Pitches 


Test 9.—Hardness or Consistency. This is largely a test em- 
ployed in connection with road-making and pavement bituminous 
materials, and detailed reference to these tests is out of place in 
the present volume. The familiar Moh’s Hardness Scale is used 
to some extent, but the Needle Penetrometer % % °4 measures 
the “‘ Penetration, which is defined as the consistency of a bituminous 
material, expressed as the distance (usually in hundredths of 1 cm.), 
that a standard needle vertically penetrates a sample of the material 
under known conditions of loading (usually 100 grams), time (usually 
5 seconds) and temperature (usually 77° F.).” A full description 
of this apparatus, together with an allied one, the Consistometer, is 
given by Abraham. The Susceptibility Factor (Test 9d) is a 
numerical expression representing the susceptibility of a bituminous 
substance to temperature changes. It is calculated from the 
consistometer hardness and fusing point (K. and 8.) thus: 


Rane cnehiife (Hardness at 32° F.) — (Hardness at 115°) 
Fusing Point (K. and 8.) 

and is obviously purely an empirical relationship. Usually this 

factor is under 40 for blown petroleum asphalts and fatty acid 

pitches, between 40 and 60 for residual asphalts, and over 60 for tar 

pitches and asphaltites. 

Tests 10, 11, 12.—Ductility, Tensile Strength and Adhesiveness 
have the physical significance ordinarily attached to these terms, 
and the tests are mainly of interest in testing road-making bituminous 
materials. 





x 100, 


Heat Fests. 


Test 13.—Odour on Heating. Most of the manufactured 
residual pitches may be recognised by characteristic odours emitted 
on heating. 

Test 14.—Subjection to Heat. A study of behaviour on melting 
and heating in a flame is often a valuable guide to identification. 
Many bituminous materials, especially those of low susceptibility 
factor, melt sluggishly and have an intermediate pasty stage before 
reaching complete liquidity; noticeably is this the case with 
blown petroleum asphalts and many fatty acid pitches. ; 

fest 15.—Fusing or Melting Point. The determination of this 
point raises much controversy from the fact that in strict scientific 
parlance the term is somewhat of a misnomer when applied to the 
complex mixture of fatty acids, hydrocarbons, asphaltic, resinous 
and other compounds which may constitute a bituminous material ; 


Methods of Testing Bituminous Materials and Pitches 87 


such a substance cannot have a definite melting point, but on 
heating it passes more or less gradually from hardness through all 
stages of plasticity to complete liquidity, and the actual tempera- 
ture recorded as the m. p. or f. p. is that at which the material is 
sufficiently soft to flow. 

A somewhat elaborate method has been devised by G. Kramer 
and C. Sarnow °° (K. and S. method), and modified and elaborated 
by H. Abraham. A method called the Cube Method (Test 15c) 
has been applied to tar-pitches,®°* and a modification of this, due 
to W. Mansbridge,*’ is preferred for all ordinary purposes by the 
present author and is carried out as follows. The material to be 
tested is attached to the bulb of a thermometer, by slightly soften- 
ing until it adheres, about 6 grams of the pitch or bituminous 
material, which should cover one-third of the bulb being used. 
The thermometer is then arranged in a boiling tube (1 in. by 7 ins.), 
which is fitted into a glass enclosure itself immersed in a small 
oil-bath, which latter is heated over a small Bunsen flame to give 
a temperature rise of 2° C. per minute. The thermometer passes 
through a cork, which closes the tube and is so supported that 
the bottom of the bulb is 14 ins. from the bottom of. the tube. 
The temperature at which the bituminous material has softened 
sufficiently to fall to the bottom of the tube is recorded as the 
m. p. of the material. — 

Test 16.—Volatile Matter. This serves to identify various 
bituminous materials. The A.S.T.M. recommends to heat at 325° F. 
50 grams of water-free substance in a flat-bottomed dish 55 min. 
by 35 mm. for 5 hours in a previously heated oven.°® 

Test 17.—Flash Point. The value of this test is mainly as 
a criterion of fire risk. The Pensky—Martens Closed Tester is one 
of the most generally favoured types of tester in this country. 
Its use is admirably described in any of the standard volumes on 
technical chemical analysis, and particularly by Redwood. 

Test 18.—Burning Point. This test is supplementary to. the 
previous one. The cover of the flash-point tester is removed and 
the heating and exposure to the test-flame are continued until the 
vapours ignite and continue to burn. 

_ Test 19.—Fixed Carbon. This test is usually of value with 
natural asphaltine products, and is carried out as follows: % place 
1 gram of the material in a platinum crucible of 20—30 grams 
weight having a tightly-fitting cover, and heat for exactly 
7 minutes by means of a Bunsen flame 20 cm. high, the mouth 
of the burner being 6—8 cm. below the bottom of the crucible. 


88 Blacks and Pitches 


Cool and weigh. Remove the cover of the crucible and ignite 
over a full Bunsen flame until only ash remains. The weight 
of the first residue less the weight of ash gives the weight of wane 
carbon, which should be calculated to a percentage. 

Test 20.—Distillation Test. As this is generally a test applied 
to tars, and particularly in connection with road work, the reader 
is referred to any of the well-known works on tar or petroleum 
distillation. 

Test 21.—Solubility in Carbon Disulphide. This is often a basis 
of purchase of bituminous material. The bituminous material 
should be freed from moisture and 1—2 grams weighed into a 
150 c.c. Erlenmeyer flask and agitated with 100 c.c. of carbon 
disulphide. Filtration removes the insoluble matter. The exact 
procedure to be adopted is outlined in any of the standard works 
on analysis. The insoluble matter remaining includes both the 
non-mineral matter insoluble in carbon disulphide (Test 21b) and 
the mineral matter (21c). The former is determined by ignition 
in a Gooch crucible, and the residue represents the mineral matter. 

Test 22.—Carbenes—the bituminous substances soluble in carbon 
disulphide, but insoluble in carbon tetrachloride.1 Carbenes 1 are 
found in tar and pitches and in certain hard asphalts and asphaltites, 
but should not occur in petroleum asphalts to an extent in excess 
of 05%. The procedure is as in Test 21, replacing the carbon 
disulphide by carbon tetrachloride. 

Test 23.—Solubility in 88° Petroleum Naphtha. The method 
is performed in the same manner as for determining the portion 
soluble in carbon disulphide, 88° petroleum naphtha being substituted 
for the latter. 

Generally it happens that the harder the bituminous product 
the smaller the percentage that will dissolve in 88° naphtha, and 
this soluble portion is termed “ petrolenes”’ (also “ malthenes ’’), 
whilst the non-mineral part insoluble in 88° naphtha is termed 
‘* asphaltenes.” 

Test 24.—This calls for no comment—circumstances will decide 
the solvent to be used and the condition of extraction. 


Chemical Tests. 


Test 25.—Water. The test is mainly used for the purpose of 
dehydrating the material prior to further examination. Its detailed 
description will be found in standard volumes on analysis and on 
tar distillation. ps 

Tests 26, 27, 28, 29, 30.—Carbon and hydrogen are estimated 
by combustion, sulphur by ignition of the material in a Berthelot 


Methods of Testing Bituminous Materials and Pitches 89 


type of bomb calorimeter, nitrogen by the Kjeldahl—Gunning 1 
method, and oxygen by difference according to the procedure 
described in any of the well-known works on organic chemical 
analysis. 

Test 31—Free Carbon in Tars. This is an adaptation of 
Test 24 suitable for tars and pitches containing free carbon; hot 
benzol-toluol is the most satisfactory solvent and thorough extrac- 
tion is necessary. A special apparatus has been devised by H. J. 
Cary-Curr.18 

Test 32.—Naphthalene in Tars. The method adopted is that 
given in any of the well-known volumes on coal tar. 

Tests 33, 34, 35 are of lesser importance generally, and as they 
_ are mainly for the purpose of comparison, they need not be described 
here, but the reader is referred to C. Richardson. 

Test 36.—Mineral Matter. A detailed examination of this, the 
amount uncombined, the amount combined with non-mineral 
constituents, the chemical analysis and microscopic examination 
of the mineral matter are often of importance in connection with 
the examination of native asphalts. 

Test 37.—Saponifiable Constituents. In this connection it is 
often important to determine in fatty acid pitches, wood tar pitch 
and rosin pitch the amounts of free fatty acids, lactones and an- 
hydrides, as well as the saponification values. An estimation of 
fatty and resin acids is also desirable. The usual standard technique 
described in any of the well-known works on oils and fats is adopted, 
though it will be found convenient in many cases to use light petro- 
leum spirit as the solvent. For saponification values, the proposal 
of Marcusson 1° is to be recommended thus: 5 grams of the pitch 
or other material in 25 c.c. of pure benzol are refluxed for 1 hour 
with 25 c.c. of normal alcoholic caustic potash solution, and after 
cooling 200 c.c. of neutralised 96% alcohol are added, and the 
mixture is titrated with semi-normal hydrochloric acid solution, 
using as indicators together 3 c.c. of 1% alcoholic phenol phthalein 
solution and 3 c.c. of 1% alcoholic alkali blue solution, the colour 
change being from brownish-red to a distinct blue. 

Test 38,—Asphaltic Constituents. J. Marcusson 1° has outlined 
methods for distinguishing between native and petroleum asphalts, 
and in the detailed scheme of analysis proposed he determines free 
asphaltous acids, anhydrides, asphaltenes, asphaltic resins and 
oily constituents. 

Test 39.—Unsaponifiable and Saponifiable Matters. This test 
is of considerable value as a means of identification and as a criterion 
of quality. The customary methods are applicable after the 


90 Blacks and Pitches 


bituminous material has first been freed from insoluble constituents 
by refluxing with benzol. 

Test 40.—Glycerol. This test is of special importance in the 
examination of bituminous paints, japans, etc., as glycerol indicates 
the presence of triglycerides, which may be present in stearine 
pitches. The standard method?’ is adopted after the glycerine 
has been obtained by prior saponification. 

Test 41.—Diazo Reaction. This enables phenols to be detected, 
and is a means of identifying most of the tar pitches. The particular 
adaptation to be used is that due to E. Graefe.1° 

Test 42.—The Anthraquinone Reaction for detecting anthracene 
in tar products and 

Test 43.—Liebermann-Storch Reaction, which serves as @ 
qualitative test for detecting rosin, rosin oil, or cholesterol is the 
well-known test as described in any standard work on oils and 
fats. 

Test 44.—Iodine Value. According to Pickering 1° and others, 
this determination is not usually possible, owing to lack of a suit- 
able solvent, but the present author has obtained good results for a 
great variety of fatty acid pitches. About 0-1 gram of the material 
is dissolved in 20 c.c. of cold carbon tetrachloride, and this operation 
may require up to 2 hours. The operation is then proceeded with 
exactly as for a fatty oil by the method of Wijs. Though the 
solution is usually very dark, the colour change at the end of the 
titration is quite definite and unmistakable. , 


REFERENCES. 


89 Journ. Inst. Petroleum Technologists, 8, No. 34, Dec. 1922. % * Specific 
Gravity: Its Determination for Tars, Oils and Pitches,” by J. M. Weiss, 
J. Ind. Eng. Chem., 1915, 7, 21. 1 “‘ Technology and Analysis of Oils, 
Fats, and Waxes,” London, 1923. 2 ‘Standard Test for Penetration of 
Bituminous Materials,” American Soc. for Testing Materials, 1916, p. 530. 
93 “* Improved Instruments for the Physical Testing of Bituminous Materials,” 
by H. Abraham, Proc. Amer. Soc. Testing Materials, 1911, 11, 673. «* “The 
Testing of Bitumens for Paving Purposes,” by A. W. Dow, abid., 1903, 3, 
352. %5 Chem. Ind., 1903, 26, 55. °* ‘*‘ Methods for Testing Coal Tars and 
Refined Tars, Oils and Pitches Derived Therefrom,” by 8. R. Church, J. Ind. 
Eng. Chem., 1911, 8, 228; 1913, 5, 195. ®? J. Soc. Chem. Ind., 1918, 87, 
pt PR (Serial D6 16) ‘Amer. Soc. for Testing Materials, 1916, p. 533. 
99 J. Amer. Chem. Soc., 1899, 21, 1116. 1% Clifford Richardson and C. N. 
Forrest, J. Soc. Chem. Ind., 1905, 24, 310. 191 ‘*‘ Studies on the Carbenes,”’ 
by K. if Mackenzie, J. Ind. Eng. Chem., 1910, 2,124. 192 ** Standard Methods 
for Laboratory Sampling and Analysis of Coal ” (D 22-16), American Soc. 
for Testing Materials, 1916, p. 570. 1° J. Ind. Eng. Chem., 1912, 4, 535. 
104 “* The Modern Asphalt Pavement, ”” 2nd ed., 1908, pp. 544, BBS. 105 Zeit, 
angew. Chem., 1911, 24, 1297, 198 ‘Tbid., 1916, 29, 346. 107 « Analysis of 
Crude Glycerine,” by the International Standard Methods, J. Soc. Chem. Ind., 
1911, 30, 556. 19° Chem. Zeit., 1906, 30, 298. 1° ‘* Commercial Analysis 
of Oils, Fats and their Commercial Products,” G. F. Pickering, 1917. 


CHAPTER XII 
NATIVE ASPHALTS 


Origin and Relationship to other Naturally Occurring Bituminous Bodies— 
The Bermudez and Trinidad Pitch Lakes—Composition of Natural 
Asphalts. 


In considering the origin of deposits of bitumens and pyrobitumens 
geological considerations are of prime importance, though within 
the compass of this chapter it is impossible to make more than a 
passing reference to the subject. Bitumens and pyrobitumens, 
in all but a few cases, are found in sedimentary deposits of sand, 
sandstone, limestone and sometimes in shale and clay—only very 
rarely in igneous rocks. 

_ Bitumens and pyrobitumens are found in nature in the following 
ways 8 ;:— 


1. Overflows : 


(a) Springs—source of petroleum and liquid forms of asphalt. 

(b) Lakes—some of largest deposits of asphalt found in 
this way. 

(c) Seepages—these occur in the case of petroleum and 
liquid forms of asphalt, usually cliffs and mountain sides 
bearing impregnated rock. 


2. Impregnated Bike. 


(a) Subterranean pools or reservoirs—all the large eee 
of petroleum occur in this way. 

(b) Horizontal rock Peed oor and semi-liquid asphalts 

(c) Vertical rock strata occur in this way. 


3. Filling Veins: 
(a) Caused by vertical cleav-\ The harder asphalts, asphalt- 


age ; ites and asphaltic pyro- 
(b) Cireed by peraening : bitumens are usually found 
(c) Caused by sliding ; in fissures as a result of 
(d) Formed by. sedimenta- one or other of these opera- 


Rene . y i . J tions. 


Discussion as to the origin of bitumens and related substances 
has generally centred itself on the origin of petroleum, this being 


considered the parent substance. Amongst the theories advanced 
91 


92 Blacks and Pitches 


to account for the origin of petroleum may be cited the one that 
free metallic elements at high temperatures in the interior of the 
earth react to produce metallic carbides, which in contact with 
water produce acetylenes, and these, in turn, by appropriate 
condensations, give rise to petroleum. W. Ramsay 4 111 has 
commented on the almost universal occurrence of nickel in the 
ash from petroleums, and concludes that the catalytic reduction of 
carbon monoxide or carbon dioxide may account for deposits of 
petroleum. 

Various organic theories have been advanced purporting to 
explain the origin of petroleum from decaying vegetable matter, 
deposits of sea-weeds, etc., and in like manner petroleum and 
asphalt are considered as possibly derived from accumulations 
of animal matter and fish, which in time have decomposed into 
hydrocarbons. In this connection the work of 8. Kawai and 
S. Kobayashi !!* on a petroleum-like hydrocarbon derived by heating 
shark liver oil in contact with dry clay under pressure is interesting. 
K. H. C. Craig 11° has ably summarised the most important of the 
recent investigations bearing on this subject. 

Notwithstanding the conflicting views as to the origin.of petro- 
leum, there is substantial agreement that petroleum, once formed, 
is gradually converted into other types of bitumens and pyro- 
bitumens, the cumulative influences of time, heat and pressure 
being important desiderata. 

The view currently held is that advanced by Clifford Richard- 
son 114115 after a study of the Trinidad asphalt deposit. Here it 
is concluded that an asphaltic petroleum existing at a considerable 
depth is converted into asphalt as a result of surface action in 
which a thorough emulsification with colloidal clay, sand and 
water is brought about by the action of natural gas acting under 
high pressure. During this metamorphosis hydrogen is supposedly 
eliminated, the hydrocarbons being enriched in carbon thereby, 
and becoming structurally more complex. In turn harder asphalts, 
asphaltites and asphaltic pyrobitumens may be formed in a 
favourable environment. 

According to Peckham ™* in a review of the chemistry and 
technology of Californian bitumen and asphalt since 1865, the 
polymerisation of petroleum and the rapidity of its conversion 
into asphalt are due largely to the content of unstable compounds 
of nitrogen and sulphur in the petroleum. 

Tentatively one may consider the following series of meta- 
morphoses : 


Native Asphalis 93 


Petroleum 
Non-asphaltic Petroleum Mixed-base and Asphaltic 
Petroleums 
Mineral Waxes Asphalts 
| | 

Pure and Fairly Impure 

a (Rock Asphalts) 
Asphaltites (Impure Asphaltites) 
Asphaltic Shales, Asphaltic 
Pyrobitumens Pyrobitumens 


The non-asphaltic pyrobitumens—the lignites, coal shales, 
- bituminous coals and anthracite, are outside the scope of our survey 
and need not be considered therefore. 

We are now in a position briefly to review the more important 
native asphalts, commencing with those deposits containing less 
than 10% of mineral matter, and these we may term : 

The Pure Native Asphalts—These are found in various parts 
of the United States, notably in Utah and California, the deposit in 
the latter State averaging 85°% asphalt, 10% mineral matter and 
5% moisture and natural gas. Deposits occur also in Mexico and 
Cuba, but the most important one is that of Bermudez in Venezuela, 
the so-called Bermudez Pitch Lake, on the western side of the 
Gulf of Paria and opposite the Island of Trinidad. The asphalt 
lake extends over 900 acres in swampy land and averages 4 ft. in 
depth. Where the asphalt exudes from the springs it is quite 
soft, but the surface of the deposit hardens slowly on exposure 
and at the edge of the lake the asphalt is hard and brittle. 

According to Richardson 1 the dried crude Bermudez asphalt 
has the following characteristics : 


(Test 1) UIE DY) TASB? ces ccdent ta conacdtdensueeeoaws Black 


(Test 4) CRUE ie in Aeiinna's pape xandabavns vogne's nck gie Conchoidal 
(Test 5) Ne ica hn bss diese ok Whads sans RVbw ces dy hana Bright 
(Test 7) Specific gravity at 77°F. .....cecsscseeeee 1-005—1-075 
(Test 15d) ‘Temperature at which it flows ............ 135—188° F. 
(Test 16) Volatile at 400° F. in 7 hrs. (dried 

SEE Doc vo wer ssaurelnetusancswotnraevs renee 5:81—16-05% 
(Test 21a) Soluble in carbon disulphide ............ 90—98% 
(Test 216) Non-mineral matter insoluble ......... 0:62—6:45% 
(Test 21c) Free mineral matter — ........cccscccccsccocee 0-50—3:-65% 


The water present with this asphalt is not emulsified with the 
asphalt, as is the case with the Trinidad deposit to be described 
later. The amount of water varies from 10 to 40%. For a full 


94 Blacks and Pitches 


description of the refined Bermudez asphalt the reader must consult 
Bardwell.11? 118 

Other similar deposits are the La Brea deposit in the delta of 
the River Orinoco and small deposits in France, Greece, Eastern 
Siberia and the Philippine Islands. 

Native Asphalts associated with Mineral Matter.—Deposits are 
found in Kentucky, composed of sand and sandstones with 4—12% 
of asphalt, whilst in the State of Oklahoma are some of the richest 
asphalt deposits in the U.S.A. Here the deposits are found in 
both liquid and solid forms, and most of what is mined is used for 
paving purposes. The crude rock is-boiled with water, the impure 
asphalt rising to the surface and the sand waste settling to the 
bottom. 

Other deposits occur in Texas, Utah and California, at Alberta 
in Canada, in Mexico and Cuba. The largest deposit in the world, 
however, is that known as the “ Trinidad Asphalt Lake,” near the 
village of La Brea in Trinidad. This deposit covers an area of 
115 acres to an average (estimated) depth of 150 ft. in the centre, 
where it is undoubtedly fed by gradual seepage from below, as 
the level of the lake has dropped only very slightly in spite of the 
removal of vast quantities of the asphalt for use in pavement 
construction. 

The crude asphalt is an emulsion of bituminous matter, water 
and finely divided mineral matter, and is very constant in com- 
position. There is naturally some slight change in character, as 
the asphalt gradually flows from the centre of the lake, where it 
is softest, to the edges, where it becomes harder. P. Carmody 1° 
gives the following data : 


Other 
Water. Ash. Bitumen. organic © 

matter. 

SOLS os. 29-04% 24:1% 45:6% 1-24% 
Hard ... 21:-4—27-4% 27-4—29-:7% 40-2—42-0% 4:-4—5:0% 


Samples, after pulverising and drying at ordinary temperatures, 
show about 55% of bituminous matter soluble in carbon disulphide, 
and about 35% of mineral matter, the balance being water of 
hydration, bituminous matter adsorbed by the clay, and thus 
rendered insoluble in carbon disulphide. 

The bituminous matter of the “ lake asphalt ” is a true asphalt, 
as distinct from the asphaltites and pyrobitumens. The crude 


Native Asphalts 95 


asphalt differs only from a residual asphalt made by the distillation 
of a crude oil in respect to its large content of mineral matter 
and relatively high content of sulphur, 2—10%, usually in excess 
of 4%. | 

From one edge of the lake there is a gradual steady movement 
of asphalt towards the sea. The asphalt from this flowing sheet 
is locally known as “land asphalt,” and is not so uniform in com- 
position and differs somewhat from the “lake asphalt.’’ Carmody 
(loc. cit.) gives the following examples : 


Soft lake | Hardlake| Land Asphalt 


from 
asphalt. asphalt. asphalt. need 
% 70 % % 

Volatile matter .2..6..60...66 54-5 3°3 47-7 33°7 

Fixed carbon .......... oS Se 9-6 10:3 9-8 8:0 

ek ok oa Ven cnsarne 5:7 5-2 4°8 4:2 

ASpHaltenes .....0.....s0ccee. 14-7 16-7 10-4 7-9 
Total organic to 100 parts 

EROPDATIG: acc see scs> oss. 207°6 180-7 170-1 79-7 


The crude asphalt is refined by heating to about 160° C. to 
remove water, mechanical impurities being at the same time 
skimmed off or settled out. : 

The refined asphalt, the so-called Trinidad épuré, has the 
following properties : 


BIOCHIO STAVIGY BE ZOO. ....0ssnccserersvssesectencecaece . About 1-40 
Conchoidal fracture and dull lustre. 
Penetration (Dow) at 25° ©. 2... ...ccvccesevennecvocsenes About 7 
IRE CLOW OG 2 On a snugncsshensosnnecarancnensens PCR: 
MRNA MENTE TS, GS, O5-) os nis vinwsinuytnnees seineseusentpnans ORT: veg BP 
Bituminous matter, soluble in carbon disulphide ... Frigid ty 
Ec hnaipne vs show's gnagestsrasssttaaauensevearenr’ WE 1. by” 
Melting point of the pure bituminous matter, free 
etre AMOI) INALGOL OSS ev cscccescescvescstcossesestes 3» Ob" G; 
C. 80—82% 
ae Oo 
Ultimate analysis of the bituminous material ...... ‘a eck. To 


N. about 0:8% 
Solubility of the pure bituminous matter upon extraction cold by: 


Acetone . ; : : ey 3 ar hy 
Benzol . ; , , : 999% 
Chloroform . ‘ , . 934% 
Ethylether . : : . 689% 


Native asphalts of lesser importance occur also in France, 
Switzerland, Germany, Austria, Italy, Spain, Russia, Syria, Iraq, 
Algeria and deposits of bituminous marl in Ismid, Asia Minor. 


96 Blacks and Pitches 


Comparatively recently further light has been thrown on the 
chemical composition of the natural asphalts by the researches 
of Marcusson,!?! 122 and he subdivides these bodies into four main 
classes : 


1. Oily substances, in the main saturated and unsaturated 
hydrocarbons. 

2. Petroleum resins, or “ Petrolenes,’? which form the first 
stage of conversion of petroleum hydrocarbons into asphaltenes. 
They are brownish-black masses soluble in petroleum spirit, 
chloroform and carbon disulphide. 

3. “‘ Asphaltenes,”’ formed by the action of oxygen or sulphur 
on the resins, or by intramolecular change in these. The 
bodies are completely soluble in carbon disulphide, benzol 
and. chloroform, and contain 7—13% sulphur. These and 
the parent resins appear to be saturated polynuclear compounds 
containing oxygen or sulphur. 

4. Asphaltogenic acids, and their anhydrides—tar-like or 
resinous masses soluble in chloroform and ethyl alcohol. 


The following table is instructive : 


TABLE XX. 


Marcusson’s Subdivision of Asphalts. 





Free +] 
eaphatt- | 2000" | Asphaled etal a 
ORETIE drides. enes. | resins. | stance. 
acids. 
Bitumen from Trinidad 3 va gf % % 
STONE 5 oss ebnos es 6-4 3:5 37-0 23-0 31-0 
Bermudez asphalt ...... 3-9 2:0 35:3 14-4 39-6 


The “petrolenes”’ of Trinidad asphalt are extremely sticky 
and of cement-like nature, and not merely oily, and they (the 
petrolenes) impart to the asphalt its cement-like property. The 
““ asphaltenes ’’ impart cohesiveness as distinguished from adhesive- 
ness, and supply body and stability to the binding material. 


REFERENCES. 


110 J. Soc. Chem. Ind., 1923, 2877. 111 J. Inst. Pet. Tech., 1924, 10, 87. 
112 J, Chem. Ind. Japan, 1923, 26, 1036. 11% J. Inst. Pet. Tech., 1923, 9, 
344. 114 J, Ind. Eng. Chem., 1916, 8, 3 and 493. 115 Met. Chem. Eng., 
1917, 16, 3. 118 Journ. Franklin Institute, 146, [1], 45. 117 118 J. Ind. Eng. 
Chem., 1913, 5, 973; 1914, 6, 865. 119 J. Inst. Pet. Tech., 1921, 7, No. 28. 
120 Petroleum, 1923, 19, 576. 121,122 Zeit. angew. Chem., 1916, 29, 346, 349; 
1918, 81, 113, 119. 


Native Asphalts 97 


Bibliography—Native Asphalts. 

“The Nature and Origin of Petroleum and Asphalt,” by Clifford Richard- 
son, Met. Chem. Hng., 1916, 8, 4. ‘On the Nature and Origin of Asphalt, 
published by the Barber Asphalt Paving Co., Long Island City, N.Y., 1898. 
*“The Asphalt and Bituminous Rock Deposits of the United States,” by 
G. H. Eldridge, U.S. Geological Survey, 1901. ‘‘ Contributions to Economic 
Geology,’ Bulletin No. 213, U.S. Geological Survey, 1903. F. J. Nellensteyn, 
Chem. Weekblad, 1924, 21,42; J. Inst. Petr. Tech., 1924, 10, 311. Berginisation 
of asphalt recently studied by P. Bruylants, Bull. Soc. Chem. Belg. 1923, 


32, 194. H. I. Waterman and F. Korlandt, Rec. Trav. Chim. Pays-Bas, 
1924, 45, 249. 


CHAPTER XIII 
ASPHALTITES 


Gilsonite, Manjak and Grahamite—Their Occurrence and Characteristics— 
The Asphaltic Pyrobitumens—Elaterite, Wurtzilite, Albertite, Impsonite. 


ASPHALTITES are naturally occurring asphalt-like substances char- 
acterised by high melting points (over 250° F.), and Abraham 
recommends the following means of differentiating their three main 
classes—gilsonite, glance pitch, and grahamite—one from the other, 
as follows : 


Specific Fusibility | Fixed 
Streak. gravity at {| (K. &8.) | carbon. 
sees A jag ss oe. g 


70 
Gilsonite or uintaite ......... Brown 1:05—1-10 | 250—350 | 10—20 
Glance pitch or manjak * ... | Black 1-10—1-15 | 250—350 | 20—30 


Franearni6e-*, 2.. cies anes sa okes Black 1-15—1-20 | 350—600 | 30—35 
* When substantially free from mineral matter. 


In all three classes the non-mineral constituents are almost com- 
pletely soluble in carbon disulphide. 

These bitumens are rather narrowly distributed in nature and 
are considered by Richardson 13> 14 to be the result of metamorphic 
changes in petroleum under a particular environment. From the 
softest gilsonite, which will flow slowly on exposure, to the hardest 
grahamite not melting even at high temperatures, are materials of 
varying consistency. A hardening in consistency is accompanied 
by gradual decrease’ in the percentage amount of the material 
soluble in petroleum spirit or naphtha and an increase in the yield 
of residual coke. These differences become the more striking when 
comparison is made with other petroleum derivatives, as shown in 
the following table due to Richardson : 15 


TaBLeE XXI._ 


Comparison of some Petroleum Derwwatives. 


Specific Sol. in Saturated 
gravity at naphtha. | hydrocarbon. 
Cian o % 








Petroleum flux (Texas) Tienes: 0:956 


97-5 72:8 
Petroleum residual pitch ......... 1-089 65-0 33:1 
Bermudez asphalt ............... 1-082 62-2 24:4 
Gilsonite (Utah)  .......c.eseeeeees 1-044 47-7 5:5 
Grahamite (Oklahoma) ......... | 1-171 0-4 0:3 





99 


The relations in composition of gilsonite, grahamite and other . 
forms of natural bitumen have been tabulated in a paper by 
Mabery.!26 

Gilsonite.—This is found only in one region extending from the 
eastern portion of the State of Utah into the western portion of 
Colorado, and occurs in parallel vertical veins from a fraction of an 
inch in thickness to a width of 18 ft. The material is removed by 
a crude mode of mining. 

A sample examined by the present author *4 some time ago had 


Asphaltites 


the following characters : 


MR MUR MRR Daly gs a sy sii cmv is cnssbiacnndadvetcsesiaaesss Jet black 
NE hina sch n6i4s< sannevaseytersecensexvaane Conchoidal, the 
sample being 
very brittle 
RG incu dn tie a acincds wend ednanas ase ase s uses Very bright 
ei lenieiaa Stews avssekecsensscoanacessadesws Only 0-75% 
Solubility in carbon disulphide ................0eeeeeee 99-75% 
Melting point (drop method) ............ccceeeeeeeeenee 130° C. 
RPMI TIMACUOD onan ce ssvectcccccsscscessnedsccesveces Nil 


According to Abraham,*° gilsonite is fairly uniform in composition 


and complies with the following characteristics : 


SMT SCONE TEINS 2 css csbacesiscccccsccarctanacenssecews Black 

EM RIALIG civ acu ycctacdsentsccecssccdecccosscecdussies Conchoidal 

Nis cas pn des Avnecnsdvessnccsniechsenen=s4s% = Bright to eich 
bright 

IE ESTEE Sele kas cescrccesncstginedsesascnsessvicnsavas Brown 

iene). epecihic pravity at 77° Ft ..ccssccecseccascesas 1-05—1-10 

(Test 9a) Hardness on Moh’s scale .........scceeceseeveees 2 

(Test 9b) Hardness, needle penetrometer at 77° F. 0 

(Test 9c) Hardness, consistometer at 115° F. ......... 40—60 

Hardness, consistometer at 77° F.......... 90—120 
Hardness, consistometer at 32° F............. Too hard for test 

Pieep ud) Biaceptibility factor:  .......scccccscsccsecsoness >100 

(Test 10a) Ductility at 77° F. (Author’s method) ...... 0 

Cee y CPT OT NEALE oo iii. lec csv encecesccoatedines Characteristic 

(Test 14a) Behaviour on melting ........ccccsscccsessseeees Forms a compara- 
tively thick, vis- 
cous melt 

(Test 140) Behaviour on heating in flame ...........008. Softens and flows 

(Test 15a) Fusing point(K. & 8. method) ............+6 250—350° F. 

(Test 150) Fusing point (Ball and ring method) ...... 270—370° F. 


(Test 16) Volatile at 325° F. 7 hours (dry substance) Less than 2% 
Volatile at 400° F. 7 hours cccecssscsessovees Less than 4% 
Volatile at 500° F. 4 hours ............00000. Less than 5% 
Ae? PIMC COLDOTE iiss. ines beds) ed veteces dentenes 10—20% 
(Test 20) Distillation test. 
Die Oats vas aed Ana da ORV Yee by vaaset Oke kos 9-34% Distillate 
BN LE i van dice ie dnd bp ewe sae ai 5:35% Distillate 
Det Cocca cbank senr pendants bade tas ka 12-84% Distillate 
eee O05 ig cytes bess Sica cudneeeaugeecaaee 28-99% Distillate 
PMR BU Cl nic, connate Suna dawdeanGhidns Gian Coked 
(Test 21a) Soluble in carbon disulphide ...............46 Greater than 98% 
(Test 216) Non-mineral matter insoluble —...........666. 0—19 


SOHOKCHHEH HEHEHE H HHH OHH HHH HEHEHE EEOE 


(Test 21c) Mineral matter 


Trace—1 % 


100 Blacks and Pitches 


(Test 22), Carbomes) « \.c...0.. ccpvsnswae aces audbnranwae copay 0—4% 
(Test 23) Soluble in 88° naphtha  ..........s..seceesseree 40—60% 
(Test 24) Grams soluble in 100 grams of cold solvent :— 
Amy] acetate. ..ccipsnsncutnesncaceteeasueietns 86 
Awav] aloobol<,s.0.- ceataucusy ss cnyn ne eehs weeieee Insoluble 
AIDY] TIGALO Kuo. en peace ceedeth cr ebiane se eeeee 1 
Aniine<:’ its). 6. Geka iceaks Cereb eels Insoluble 
Bonzol ss is vcdss Seah dcouncassetbs aaenneranees 71 
Carbon disulphide sv. s.+<)se0aa7s saver tuaen ee Soluble in all pro- 
portions 
Carbon tetrachloride  Ys...eusteecs cases gana 
Chloroforna.>\.iscevsseeeessaneaea eke cones onnaenm 54 
Ethyl] acetaten' $21.4 Wis avy then dn enen em 3 
Ethyl! alcohol) sie svescs ues seneueeae hexane Insoluble 
Elthy! thor |: .sviitns os} sogdeanrecesvasteeeaeen eee Soluble in all pro- 
portions 
Naéputhia 62° \v.5.i..0-sscseuasteensactspesemeamne 
Nitsa benrene Vow. .ars euanci ss casucknenpeneeeseiee 9 
Propyl aloohol <0. aus sane sarees Insoluble 
ASTOR aio a's inv ssn ocoke acne hang cea Eee 72 
AUEPODGING 15. hs Cacnksdmevens sasdes eee r eee 60 
(Peat. 26)" Wagan oivicscscsosanciseackag thausy\aaenieene ee 88—89-5 % 
(Dest: 27))  STVReORer >. oa. oc. sarsatesnaascessseaenen ae ieee 8-5—10-0 % 
(Test 28)  Sulphay. gicscccicececnegeysuesace ts oosecekena tee 1-7—2:0 % 
(Teat 29) Nitrogen cas s<ppusdas sees danepcesuaeiea tate 0:8% 
(Tost. 30) Oxyoen oo cies 4scpestcantescnnsaaes sebeesgne cena 0—2% 
(Test 33) Paraffin scale «0.0 i53/. .ceeecetessdctoam ss dagen 0—Trace % 
(Test 35) Sulphonation residue  .........ssecccececseeeeees 85—95% 
(Test 37) Saponifiable matter -......i.s..s.scnccsosescesveve Trace 
(Test 41) . Diaze reaction ~ A ci.iss idevagessaesss scene benecen No 
(Test 42) Anthraquinone reaction ........sseccecsseoenees No 


Glance Pitch—This resembles gilsonite in external appearance. 
It always shows a brilliant conchoidal fracture. It occurs in Mexico, 
Colombia (S. America), Syria and in the West Indies. That occur- 
ring in Barbados is generally marketed under the name of Barbados 
““Manjak ”’ 12” It is claimed that no other native bitumen equals 
it in respect of its lustre, strength, melting point, intensity of colour 
and. elasticity. | 

According to Abraham, this ‘‘ manjak”’ contains sulphur 0:7— 
0:9%, 1 to 2% mineral matter, specific gravity at 77° F. about 
1-10, fusing point 320—340° F. (K. & S. method), fixed carbon 
25—30%, and 97—98% of the bitumen is soluble in carbon 
disulphide. : 

R. H. Emtage 128 also quotes the following analysis for Barbados 
‘“ manjak ’—carbon 83-62%, oxygen and nitrogen 2-05%, hydrogen 
8:29°%, sulphur 0-85%. Water to the extent of 2-499% and ash 
2:70% are recorded. 

According to Abraham,*° Glance Pitch complies with the following 
characteristics : 
(Test 1). ..Colour in mess v)..0....css os «saa eaes eae er Black 


(Test 4) BrAGQre ocicsicccicnsessas kon user emeeaeeepanee ... Conchoidal to 
hackly 


Asphaltites 101 


IE 1k MUI Sy cao dds es ci Chivecy vehVscvsseneseds cancers Bright to fairly 
7 . bright 

Pee 0) teal On Porcelain ...........ecessensasvenceses Black 

Pee)  pecibepravity ab 77° Foes cc ccsesencendons 1-10—1-15 

(Test 9a) Hardness, Moh’s scale .............ccceeeeceneees 2 

(Test 9b) Hardness, needle penetrometer at 77°F. . 0 

(Test 9c) Hardness, consistometer at 77° F. ..........++ 90—120 

(Test, 92) Susceptibility factor  .........cccsccecccccvssees >100 

Wemernee Iemetatitys At 77? Fe ccssesiec caters es sveceiges: 0 

Set BAICIOMT OF) TNOALING ., 0000s. cersnvectesscestscsscacs Asphaltic 

(Test 14a) Behaviour on melting ............ccscccesesveees Forms a compara- 


tively thick and 
viscous melt 


(Test 14b) Behaviour on heating in flame ............... Softens and flows 
(Test 15a) Fusing point (K. & 8. method) ............... 250—350° F. 
(Test 156) Fusing point (Ball and ring method) ...... 270—375° F. 
(Test 16) Volatile at 325° F. 7 hours (dry substance) Less than 2% 
wormere ot 400° Ff. * 7 hours’ .o.s.ccccdsccseces Less than 4% 
RNS MEME COPION, ooo ncvccccccccencacssevccsssccvevcen 20—30% 
(Test 21a) Soluble in carbon disulphide .................. Usually greater than 
; 95% 
(Test 216) Non-mineral matter insoluble _............... Less than 1% 
RPE) UITIONVAL TAGGED... ccc cc cccscccecesteseccosacoaces Less than 5% 
SEE, MRE eres. oUc du'davicu sos cct'e wens voussecect Less than 1% 
(Test 23) Soluble in 88° naphtha .............cccseeveees 20—50% 
RUE TRIES gee Vice cca descVscesccsdebccssincncceosaces 80—85% 
UE REAPER eos snd chp eeaicnsi¥edeedaeucejescaseds 7—12% 
EE ENN axis chs sscnceegeqercdcsesccearcynsscns 2—8% 
(Test 29) Nitrogen and oxygen ......c.ccssccesccssevevens A trace to 2% 
eR EPI yc spina iless enue Abusbioascevekssceocde 0—trace % 
(Test 35) Sulphonation residue  .........scceseccesescceees 80—95% 
(Test 37) Saponifiable matter ...........cccccccessencescccs Trace 
ee Ey FOACTION eis cisesees cecccccceccsescucesce No 
(Test 42) Anthraquinone reaction .........sccscceseeeeees No 


Grahamite.—This asphaltite may be very pure or may be 
associated with as much as 50% of mineral matter. It occurs in 
West Virginia, Oklahoma, Colorado, Mexico and Cuba. It is found 
in veins of varying thickness from which it is mined. 

A number of veins of grahamite are mined also in the island of 
Trinidad, and near San Fernando, on the west coat of the island, 
occur deposits of the so-called “ manjak.” Its properties are as 
follows : 


EME PAVIRU EG 20 CO, oa cccuntcrnsanecesserssvsncaves ss About 1:17 
MRCS ARs OE IS.) sven nsccrdhexsnesancnsengoaneiens 175—225° C. 
MRL. 5. 50 bc os anvanss ps aioes ads pskaneh wae hee on About 33% 
ROMS Ti PALOON, CIGUIPHIGS. . 42.00. csercesevacsncsennsey 92—96% 
ze sete COMPRCRLOSICE. Soiscesevnccheudncs smtee About 54% 
= petroleum ether 88° Be ......ccscccsscevsees 13—18% 


The largest vein is that worked at the Vistabella mine. The 
composition of the product throughout this vein is not constant; 
at the edge the manjak is amorphous or coal-like in character ; 
at the centre it is lustrous and like gilsonite in appearance. The 
melting point of this latter type is lower and its solubility in 


102 Blacks and Pitches 


petroleum ether,—viz., about 55%—is much greater. The dis- 
tillation test is as follows : 


Below 160°, sk ntetiege ee alee 0-5% 


£BO—= BOO" CC. iG ccchcancs cst eeeneeaye names 26:5% 
Above S007-C. chiwcisapiennty cope seees cree 18-:0% 
Carbonaceous residue —.....ssseessccosences 55:0% 


This “‘manjak” yields on extraction with acetone and sub- 
sequently with chloroform 12-06% of “ petrolenes’’ and 83-19% 
of “ asphaltenes ” with 4:75% of insoluble residue.129 

Grahamite, in general, according to Abraham °° complies with the 
following : 


(Test 1) Colour.in ‘manasa |, 5.2.5 s0n+sarshesideceeotseansee teen Black 

(Test. 4) PraQtare . cis cscacctesessxecberp neh <dees ieee ae Conchoidal to 
hackly 

(Test -° 8). cL MSt0e y, vives deen cecanteamkh cas antens anaeeeee ieee Very bright to dull 

(Test 6) Streak on porcelain |.......ccwscesses0eunaeeee Black 


(Test 7) Specific gravity at 77° F. :— 
Pure varieties (containing less than 10% 


mineral MMAGbOr) <<....sacekankess Spann cna 1-15—1-20 
Impure varieties (containing more than 
10% mineral matter) ....¢:.sss~sssnnaceee 1-175—1-50 
(Test 9a) Hardness (Moh’s scale)  ......ssscceeeesceeeeees 2—3 
(Test 9b) Hardness needle penetrometer at 77° F. ... 0 
(Test 9c) Hardness, consistometer at 77° F............. Over 150 
(Test. 9d) Susceptibility factor  ..cceccsesnssenssesaesnemus 100 


(Test 146) Behaviour on heating in flame :— 
Variety showing a conchoidal fracture 


and‘a black lustre. <..i00.ssuseepseseeunnin Decrepitates 
violently 
Variety showing a hackly fracture and a 
fairly bright to dull lustre. ............ Softens, splits and 
burns 
(Test 15a) Fusing point (K. & 8. method) ............... 350—600° F. 
(Test 15d) Fusing point (Ball and ring method) ...... 370—625° F. 
(Test 16) Volatile at 500° F. 4 hours .................. Less than 1% 
(Test 19) ~Pixed €arbon i....00 iiivenss saaktancaxs cet eee 30—55% 
(Test 21a) Soluble in carbon disulphide ...............0+. 45—100% 
(Test 216) Non-mineral matter insoluble in carbon 
disulphide Ty .icisisceehecsdascawees resend Less than 5% 
(Test 21¢) Mineral matter 1)iinc...)iasu~Jewaiaeek eee Variable (up to 50%) 
(Test 22). Carb@nee ©. cisasensdsdcanvagy iy peenres enone 0—80% 
(Test 23) Soluble in 88° petroleum naphtha ............ Trace to 50% 
(Test 30) Oxygen in non-mineral matter ............... 0—2% 
(Test.33}° Paraffin 0 issiiiisacee'sscessdcecaseolessdes bs aaneee 0 to trace % 
(Test 35) Sulphonation residue ...........cceseccenesevees 80—95.% 
(Test. 37) Saponifiable matter’... .......55-ccs san eesnaeenee Trace 
(Test-41) °Diazo reaction © 0.0. .c Lien coke ana No 
(Test 42) Anthraquinone reaction ...........cceessceeeees No 


In general, grahamite is characterised by the following features : 


1. High specific gravity ; 

2. Black streak ; 

3. High fusing point ; 

4. High percentage of fixed carbon; 

5. Solubility of non-mineral matter in carbon disulphide. 


Asphaltites 103 


Asphaltic Pyrobitwumens.—These are naturally occurring sub- 
stances composed of hydrocarbons characterised by their infusibility 
and comparative freedom from oxygenated substances. The prin- 
cipal classes, usually containing less than 10% of associated mineral 
matter, are as follows: 


Specific Fixed 
Streak. gravity carbon. 
at 77° F. % 
3 Light brown 0-90—1-05 2—5 
yD a re Light brown 1:05—1-07 5—25 
EATER, 6 oak sh pniuncsscce vase Brown to black 1:07—1-10 25—50 
PAUP sinc is dnevcrecs. Black 1-10—1-25 50—85 


All these are results of petroleum metamorphosis. 

Hlaterite is found in England, Australia and near L. Balkash 
and has little beyond scientific interest. It was discovered in 
Derbyshire in 1673,1°° is moderately soft and elastic, contains 6—7% 
ash and is slightly soluble in ether. 

Wurtzilite is found only in Utah,1*! occurring there in veins of 
varying width and length. It is characterised by being sectile and 
cutting like horn; if bent too far or suddenly it snaps. Its principal 
tests are quoted by Abraham as follows: . 


ERE as, in alanc hcrccceesd sues aur s¥ecestnss Black 
OS CTE VICY. A607" Fs... cov ssccseevesercaapens 1-:05—1-07 
Hardness, consistometer, 77° F. oe... eee eee ees Over 150 


(On heating in a flame it softens and burns quietly, but 
does not fuse without decomposition.) 


SRD MOER 0 ov anndb pasGeedbrracds svov nave arvve ene 5—25% 
SPINEL TIUATLOT hn. sssasrorsnsccsesssnvecmercssnaass 0-2—2-5% 
i oss tno oakn kel paras tsainnner cess ses 5—10% 
EMMIS RE (Osi syigs Son vias wou dp.) cs 5 08s bocca dahooaga About 80% 
IN ie Sil ou danipesianicns xs banpagehsnaibile 10—12% 
Ei abcd cons vatdensnn¥ind 460% sea vunlevardecmied te 46% 
EE Pn 2 20nd valk wis bb sbiy ws viba cae sonpees vues About 2% 


Albertite occurs in New Brunswick, Nova Scotia, Utah, Tasmania 
and in West Africa. It is characterised by its infusibility, insolu- 
bility in carbon disulphide, specific gravity (1:07—1-10 at 77° F.), 
fixed carbon 25—50°% and small percentage of oxygen (less than 
3%). At one time this product was utilised to enrich bituminous 
coal in the manufacture of coal gas. 

Impsonite represents the final stage in the metamorphosis of 
asphaltites and asphaltic pyrobitumens. It is characterised by its 
infusibility and insolubility in carbon disulphide and comparatively 
small percentage of oxygen (less than 5%). 


104 Blacks and Pitches 


The most important deposits are found in Oklahoma, Arkansas, 
Nevada. 

Somewhat allied are the asphaltic pyrobituminous shales and 
the non-asphaltic pyrobituminous shales, in the latter of which are 
associated the cannel coals, torbanites and pyropissite. For further 
information on these latter substances the reader is referred to the 
publications of Watson Smith,!? Baskerville and Hamor }** and 
others. 


REFERENCES 


123 “ Gilsonite and Grahamite,’’ by Clifford Richardson, J. Ind. Hng. 
Chem., 1916, 8, 496. 1%* ‘* Grahamite, a Solid Native Bitumen,”’ by Clifford 
Richardson, J. Amer. Chem. Soc., 1910, 82, 1032. 125 J. Ind. Hng. Chem., 
1916, 8, 493. 126 J. Amer. Chem. Soc., 1917, 39, 2015. 127 Oil and Colour 
Trades Journal, 1919, 56, 2093. 4128 ‘‘ The Mineral Industry during 1908,” 
17, 71. 1°° Bulletin of Imperial Inst. (Supplement to Board of Trade 
Journal), 1903, 4, 180. 1° Lister, Phil. Trans., 1673. 131 W. P. Blake, 
Trans. Amer. Inst. Mining Eng., 1889, 18, 497. 132 J. Soc. Chem. Ind., 
1909, 28, 398. 183 “‘ American Oil Shales,’ 8th International Congress of 
Applied Chemistry, 1912, 25, 631. 


CHAPTER XIV 
PETROLEUM ASPHALTS, OR RESIDUAL PITCHES 


Occurrence, World’s Production, and Refining of Petroleum—Characteristics 
of Residual, Blown and Sulphurised Petroleum Asphalts. 


VeERY closely allied to the native asphalts are the residuals from 
the distillation of petroleum, not only by reason of similarity in 
appearance and in chemical composition, but in virtue of similarity 
of applicability. These petroleum asphalts are jet-black shining 
solids, often brittle and usually showing a conchoidal fracture, 
having a low ash content, usually about 0-1%. With the exception 
of the Mexican residuals, they contain only small amounts of 
sulphur, so that in these two latter respects they are in marked 
contrast to the native asphalts. 

Petroleum occurs in different parts of the world, and varies 
widely in composition. The extent of its production is shown in 
a table recently prepared by Mr. George Sell, published in a paper on 
“‘ Crude Oils of the Empire ’”’ 1*4 (see Table XXII, p. 106). 

From the standpoint of this chapter, petroleums may be divided 
into three groups : 


1. Those bearing a substantial quantity of solid paraffins, 
usually associated with open chain hydrocarbons. 
2. Those bearing a substantial proportion of asphaltic bodies, 
usually associated with cyclic hydrocarbons. 
3. Those of mixed composition, bearing both solid BeAeng 
and asphaltic bodies. 


Paraffinoid hydrocarbons predominate in the petroleums produced. 
in Pennsylvania, West Virginia, Lima (Ohio), Canada and Alaska, 
and the residues do not yield asphalts on distillation. 

Mixed base petroleums covering both asphalts and paraffins 
occur in Illinois, Texas, Mexico and Roumania. 

Cyclic hydrocarbons predominate in petroleums produced in the 
Mexican Gulf field, California, Trinidad, and these fields yield 
asphaltic petroleums. In the case of the Borneo field, some of the 
petroleum here is asphaltic, whilst some has a paraffin base. The 
Baku field gives a petroleum in which the cyclic hydrocarbons of 
the C,H,, series—the naphthenes—predominate, though the oil is 
not asphaltic. 

After dehydration crude petroleum is fractionally distilled, the 
process being intermittent or continuous, and both methods are 
employed either with or without steam: in the latter case the 


distillation is said to be dry. 
: 105 


106 


Blacks and Pitches 


TABLE XXII. 


World’s Production of Petroleum. 


(In Imperial gallons.) 





1923. 
Estimated 
or based on 
preliminary 

returns. 


— | ES | | 


United States |15,519,070,000 |16,526,305,000 |19,513,585,000 |25,399,570,000 


Mexico 
Russia 
Eastern 
Archipelago 
Persia 
Roumania... 
Galicia......... 
POP So cess 
Japan and 
Formosa... 
Argentina ... 
Venezuela ... 
France: ..<.. 
Germany...... 
SIAL Osan css 


British Empire— 
India 


Egypt 
Sarawak ... 
Canada .... 
United 
Kingdom. 


eeveee 


6, 


103,089,600 | 6,460,129,200 | 6,370,000,000 | 5,233,544,000 
907,500,000 924,000,000 | 1,209,000,000 | 1,344,000,000 
585,541,500 588,464,400 585,189,000 583,000,000 
394,703,100 505,660,500 665,081,700 846,487,700 
263,875,300 301,846,100 354,678,700 391,340,400 
196,062,200 180,694,400 182,804,200 188,831,000 
98,582,700 125,000,000 127,000,000 128,000,000 
93,205,000 91,000,000 90,000,000 88,000,000 
50,963,600 51,247,500 71,087,400 80,000,000 
17,360,000 50,000,000 70,000,000 100,000,000 
13,601,800 13,766,500 19,101,000 17,511,900 
8,418,700 9,000,000 11,000,000 13,000,000 
1,360,500 1,317,300 1,300,000 1,300,000 
293,116,800 305,683,200 298,504,100 298,000,000 
72,906,000 82,395,600 85,566,300 90,000,000 
37,281,100 51,376,000 45,000,000 35,000,000 
35,138,100 49,632,200 100,178,900 135,000,000 
6,868,800 6,563,900 6,267,400 6,160,000 
102,100 91,400 32,800 7,500 


ee ee | | | eS 


Total 


Figures in black are estimated. 


... |24,698,746,900 |26,324,173,200 |29,805,376,500 |34,978,762,500 


For full details as to the operation of petroleum distillation the ~ 
reader must have recourse to the works of Redwood 1%5 and Camp- 


bell,18° but in bare outline two refining schemes may be quoted, due 
to A. E. Dunstan and J. Kewley: 1%4 


Topping Scheme. 


Crude oil distillation. 


| 
Petrol from 
pre-heater. 


Benzine. 


Crude | ge 


Crude benzine. 
Redistillation. 


Residue. 


~- Kerosene. 


Redistillation. 
| 


Residue 


Residue 
fuel oil. 


Petroleum Asphalts, or Residual Pitches 107 
Full Refining Scheme. 


Crude oil distillation. 


Petrol from Crude benzine. Once-run Heavy 


pre-heaters. Redistillation. kerosene, residue, 
pitch or 
coke. 
Benzine in Residue. Redistillation. Loss, 
one or more 
grades. 
Kerosene. Intermediate oil. 


Heavy oil and paraffin 
Redistillation. 


| 
2nd stage H. O. & P. Residue, 
In one or two fractions. pitch or 
Refrigeration. coke. 


5 Loss. 


Paraffin scale. Filtrate. 
Fractional sweating. Lubricating oil base. 
Refractionation or concentration. 





| 
High ating point Low melting point 
wax. wax. 
Decolorisation. 
Candle manufacture. 


The main refinery products are given in Table X XIII below : 154 


TaBLeE XXIIT 
Principal Refinery Products from Crude Petroleum. 


Specific Initial and 
Name. gravity final boiling Remarks. 
range. points, ° C. 
Naphtha . 0-728—0-759 95—150 — 
Gasoline \Benzine eats 0-639—0-780 31—190 ee 
TROT OMENG. 5 oss sei iscs ices 0-785—0-811 140—310 — 
PRAMAS chicka Sinu decays ss 0-816—0-855 300—350 —— 
Ee ren 0-85 —0-96 300 and Not more than 
upwards 1% of sulphur. 
Lubricating oil ......... 0-882—0-905 300 and Free from sul- 
upwards phur and 
; asphalt. 
Residual oil ..........5.:.. 0-928—0:96 — — 





The residual products obtained in the distillation of petroleums 
are represented by the following classes, according to Abraham : 


108 Blacks and Pitches — 


(a) Residual Oil.—The residue from the dry-distillation of 
paraffinoid petroleums, the steam or the dry distillation of mixed- 
base petroleums and the steam distillation of asphalt-bearing 
petroleum. This residual, termed liquid asphalt, petroleum flux, 
etc., is liquid or semi-liquid at the ordinary temperature. 

(b) Residual Asphalt,—The residue from steam or dry distillation 
of mixed base and the steam distillation of asphalt-bearing petro- 
leums. 

(c) Blown Asphalts.—The products obtained by blowing air 
through residual oils at high temperature. | 

(d) Sulphurised Asphalt.—A product obtained by heating residual 
asphalt with sulphur at high temperature. 

(ec) Sludge Asphalt.—The asphalt-like body separated from the 
acid sludge produced in the refining of petroleum distillates with 
sulphuric acid. The newer methods of refining petroleum will 
doubtless eventually eliminate this type of residual. 

(f) Petrolatum or Vaseline. 

The following yields are obtained from a California asphaltic 
petroleum : 187 


Gasoline (60? BG.) .<issessiedacenuencabeut texcessenes Trace—20% 
Naphtha (66° 336.) ....0:ss0ssteaesenstqnateeastemeaenes Trace—15% 
Kerosene (35—42° Bé.) ....cccccccceseccsescccccceece Trace—30% 
Gas or fuel oil (25—30° Bé.) .........ccccseeeseseees 10—40% 
Lubricating oil (17-—25° Bé.) — .......scesscccveveee 15—70% 
Ftesidual asphalg .....cssccesanoncedetseuvenstnaccieenny 20—40% 
LpDGE \ nninas cup niane cnn tase bouseehdsoeduive humans oat atiaeee 1—4% 


The characteristics of residuals depend on the following factors : 


(a) The nature of the petroleum from which they are derived. 

b) The extent to which the distillation is carried. 

(c) The method of distillation employed and the care with — 
which the operation is conducted have some bearing on the 
result also. 


Residual asphalts in general comply with the following charac- 
teristics given in a table due to Abraham : 


(Test 1) -ColQur $23, 2098 2. o0.5 cx adeaeetccabheis aes Black 

(Test 2) ‘Homogeneity, ....2.cs-egenecttesandesnasnee ee Variable 

fToats 4) PROC ure Sixes vacag cus ecdeanayepaheuken menses ait Conchoidal in case 
of hard residues 

(Test 6) Streak om porcelain ........cscccsccccesessooes Black 

(Test 7) Specific gravity at 77° BF. ......cscccsseeees 1-00—1-17 

(Test 96) Penetration at 77° FB.  ........cccceescceeeeees 150—O 

(Test 9c) Consistency at 77° Br. ..cccsscsecedeccccoccnes 5—100 

(Test 9d) Susceptibility factor  ...........c.cceceeeeees 40—60 

(Test 11) Tensile strength at 77° F.  .......cceseeeees 0-5—10:0 | 

(Test 15a) Fusing point (K. & 8.) ....... kien ye eae 80—225° F. 


(Teat.17) > Blesh point s (....carcasacendendbiameensaten anes 400—600° F. 
(Vest 18)" Barnine poine itscs ss ncane eee eens enna 450—700° F. 


Petroleum Asphalis, or Residual Pitches 109 


DRE SET AERA CATON Wiviyecs a biinassuacetedeccaresecdee 5—40% 
(Test 21a) Soluble in carbon disulphide ............... 85—100% 
DAME BAC) MAITIOTAL INALLOL .. occ cccececsccscsusecesvaccseees 0—1% 
(Test 23) Solubility in 88° naphtha ................45 25—85% 


Carbon 85—87%, Hydrogen 9—13%, 
Sulphur trace —10%, Nitrogen trace 
—1%, Oxygen 0—2-5% 
Saponifiable constituents  .........seseeeeee 0—2% 
Some petroleum residual pitches examined by the present author *4 


showed the following characters :— 


Specific 

gravity at | M. p. (° C.). art 

15-5° C, ‘ 

_ Residual pitch from— 

An American petroleum I . 1-045 82—83 0-07 
9 - $s 9 Roe 1-060 110 0-08 
A Mexican petroleum ...... 1-001 122 0-12 
An Asiatic See ae ae 1-107 65—67 | 0-72 


None showed more than a trace of saponifiable matter, and except 
in the case of the Mexican variety, sulphur was present only in 
trace. 

According to Marcusson,!%8 petroleum residual asphalts or 
pitches do not contain asphaltogenic acids, and the proportion. of 
oily constituents (and their characteristics) depends on the extent 
of the distillation, but the amount is much greater than in the 
natural asphalts. The residues from some of the American petro- 
leums contain notable quantities of aromatic hydrocarbons, such as 
anthracene, phenanthrene, chrysene and pyrene. Further, these 
residual asphalts are insoluble in water, acids, alkalies and only 
slightly soluble in alcohol, though readily soluble in benzol and 
carbon disulphide. 


Blown Residual Asphalts. 


Air-blown asphalts derived from residual oils derived in turn 
from asphaltic mixed base or non-asphaltic petroleums have been 
manufactured for many years since they were first reported upon 
by Gesner in 1865, and the first commercial scale operation was 
brought about by F. X. Byerley in 1894.18° Generally, air and 
steam are blown into the residual oils at 270—300° C. for 10 to 24 
hours. The advantages of “‘ blowing” over steam distillation are 
that it is easier to produce an asphalt of a particular grade and of 
better quality, and, in addition, the asphalt acquires a somewhat 
rubber-like property. Moreover, the yield of asphaltic residue from 
“blowing ” is greater than by steam distillation. 


110 Blacks and Pitches a 


What the chemical changes are during blowing is uncertain, but 
D. Holde and S. Weill 44° have examined some of these blown 
asphalts, and find their saponification values increase with rise of 
melting point. In general, blown asphalts comply with the follow- 
ing characteristics : °° 


(Test 1) © Colony im aan} 2S. avh weet dat aen eeeeec ae Black 
(Test 2a) Homogeneity to the eye at room tempera- 
PATO: ions sunsare ctubu cas uns haa ene emeeae ies ane Uniform to gritty 
(Test 2b) Homogeneity under the microscope ......... Uniform to lumpy 
(Test 3) Appearance surface aged indoors one week Bright to dull and 
greasy 
(Test 4) Pragya ss ssccc cas cncadeetohnoswicescees cuae eevee Soft grades do not 


show a fracture, 
hard grades pre- 
sent a conchoidal 


fracture 

{Peat 67%. LUstre 24 ane dasevewhian> pacntawhsncne ooeeanraneem Bright to dull 

(Test 6) Streak on porcelain .........6<.)..nscscuutaeasvan Brownish-black to 
black 

(Teast 7)--Specific gravity at: ITF. ian See 0-90—1-07 

(Test 9c) Consistency at 77° Br. ....ccccccscccccccescencens 2—30 

(Test 9d) Susceptibility factor  ......ccccsscsscscccsecsees 8—40 

(Test 10)  Ductility © o.......Nidac. ivackes divas casket Variable 

(Test Tl} ‘Tensile strength “..n..cisssacsncekectwavarcyeeras Variable 

(Test 15a) Fusing point (K. & 8. method) ............... 80—300° F. 

(Test 156) Fusing point (Ball and ring method) ...... 100—325° F. 

(Test 16) Volatile matter, 500° F.in 4 hours ......... I—12% 

(Test 210) Flags pO © \<sjccresvwedd ses sp varaet tenn gee cee 350—550° F. 

(Test 18). “Burning ‘potint 5 is ccvadekedsdectsaheeeagtn ine gee 400—650° F. 

(Test 19) -Wisced carbon ..$i vcssna oceessdpescamie gi scegsenoceee 5—20% 

(Test 21a) Solubility in carbon disulphide ............... 95—100% 

(Test 216) Non-mineral matter insoluble ............... 0—5% 

(Test-21¢c) Mineral miatter .i).scdesks ies sinsenseey ems 0—3% 

Test22) -Darbenes ..,..+.cassbsatavsstadeesag pakanen er ee 0—10% 

(Test 23) Solubility in 88° naphtha ...................4. 50—90% 

(Test 24) Solubility in other solvents  ...............00. Largely soluble in 


turpentine and 
benzol, and 
slightly soluble in 


alcohol and acetone 
(Test 25) Water «25. ccoscekenerguen ee ni ruca mentee uae ane Absent 
(Test.28): Sulphur .o5ccsdesscsacnceaees teeth aiecereeaeen Trace —7:5% 
(Test:30). Oxy Gert» .5..s5.casesecsepuch avai Cask aseseeehtcnreae 2—5% 
(Test 33). Parefiits 3.0005. crvacsakewes us stiecastecesnctermerneaun 0—10% 
(Test 34) Saturated hydrocarbons ............scsseseeeees 30—75% 
(Test 35) Sulphonation residue  ...........cccscceecsceeees 90—100% 
(Test 37) Saponifiable constituents  .............ceeeeeee Trace —2% 
(Tost 20) GiyOerol ive akaks een cana ancien aralies poem None 
(Test 43). Diazo reaction” ...ccccscsasdtsccteanckene saccnaunene No 
(Test 42) Anthraquinone reaction . ........csceceseereeeees No 


Sulphurised Asphalts. . 

Under the action of heat, sulphur has a sort of condensing action on 

asphalt—analogous to vulcanisation possibly. Abraham represents 
the process roughly as C,H, + 8 = C,Hon-. + HS. 


Petroleum Asphalts, or Residual Pitches 111 


Numerous patents have been effected for sulphurising asphalts, 
fatty acid pitch, coal-tar pitch, grahamite, etc., but the use of 
these sulphurised bodies has generally been abandoned. 

Recently, however, H. Burnice 144 has treated residues from 
Roumanian crude oil with about 7:-5% sulphur, and claims to have 
produced a particularly good product. 


Sludge Asphalts. 


These are not now produced to the extent that formerly obtained. 
They are characterised by the following features: intense black 
streak, high percentage of sulphur, high percentage of oxygen, 
which distinguishes them from all other forms of asphalt and the 
_ small amount of paraffin and saturated hydrocarbons they contain. 

Much discussion and investigation have centred on the problem 
of satisfactory methods for differentiating the various natural and 
artificial asphalts and bitumens, and one may cite as references the 
publications of Hutin,!*# Graefe,14* Pailler,444 Marcusson 14° and 
Richardson.“ The conclusions drawn by the last-named investi- 
gator are particularly noteworthy, for it is shown that the natural 
Trinidad and Bermudez asphalts consist largely of unsaturated 
hydrocarbons, and following in order of increasing percentage of 
saturated hydrocarbons we have respectively Trinidad residual 
pitch, Mexican petroleum pitch, Californian petroleum pitch, and 
Texas petroleum pitch. From this follows the very important con- 
clusion that the greater the percentage of saturated hydrocarbons 
in a bitumen the less pronounced are its asphaltic characters. 

K. C. Pailler 147 has pointed out the differences between natural 
and petroleum residual asphalts based on estimation of the fixed 
carbon, the acidity of the liquid obtained on careful dry distillation 
and on the saponification value. 


REFERENCES. 


134 Dunstan and Kewley, Journ. Inst. Pet. Tech., 10, No. 44, July 
1924. 135 “A Treatise on Petroleum,’’ Sir Boverton Redwood, 4th ed., 
3 Vols. 1922. 156 ‘‘ Petroleum Refining,’ by Andrew Campbell, 2nd ed., 
London, 1922. 137 Bulletin No. 32, California State Mining Bureau. 158 Zevt. 
angew. Chem., 1918, 31, 113,119. 1° U.S. Patents 237,662 and 239,466 of 1881. 
140 Petroleum, 1923, 19, 541. 141 English Patent 188,354. 14% Caoutchouc 
et Guttapercha, 1916, 18, 8994. 143 Zeit. angew. Chem., 1916, 29, 21. 444 J. 
Ind. Eing. Chem., 1914, 6, 286. 145 Zeit. angew. Chem., 1913, 26, 91. 148 J. 
Ind. Eng. Chem., 1916, 8, 319. 4147 J. Soc. Chem. Ind., 1919, 38, 940a. 


Bibliography—FPetroleum Asphalts. 
J. M. Weiss, J. Ind. Eng. Chem., 1918, 10, 732 and 817. J. Marcusson, 


Mitt. K. Materialpruf, 1918, 36, 279. ‘‘ Detection of Natural Asphalt and 
Petroleum Pitch,” F. Schwarz, Chem. Fett. Harz. Ind., 1913, 20, 28. 


CHAPTER XV 
COAL-TAR PITCH AND ALLIED PITCHES 


Residuals in Pyrogenous Distillation—Occurrence, Genesis and Composition 
of Coal—Destructive Distillation of Coal—Composition, Properties and 
Uses of Coal Tar—Coke Oven, Producer Gas and Blast Furnace Tars— 
Distillation and Properties of the Resultant Tar Pitches. 


In this country the best known pitch and that produced in by far 
the largest amount is the familiar Coal-tar Pitch, and under this 
heading will be considered the pitches corresponding to the tar 
recovered as by-products from bituminous coal carbonised or 
consumed. in f 


1. Illuminating Gas Works. 3. Blast Furnaces. 
2. Coke Ovens. 4. Gas Producers. 


According to a recent return,148 the quantities of Tar Pitch pro- 
duced in Great Britain in the years 1922 and 1923 were as follow : 


1922. 1923. 
From gas and coke-oven works ...... (tons) 490,573 624,641 
From Other Works cess crntsisscansatesena (tons) 23,663 52,721 


The consideration of the production of the tars themselves is 
rather outside the scope of the present volume, and the reader is 
referred to any of the well-known works on Gas Manufacture, etc., 
for full information. It is not out of place, however, to point out 
that tars constitute the volatile and oily decomposition products 
obtained in the pyrogenous treatment of bituminous and other 
organic substances, such as shale, peat, greases, etc., and the result- 
ing distillates are usually of liquid consistency, dark brown to black 
in colour, and have an odour usually characteristic. The synopsis 
reproduced on p. 113, due to Abraham, indicates the raw materials 
used and the modes of treatment. 

The temperature to be employed depends much on the materials 
to be decomposed, but high temperatures result in the formation 
in the tars (and hence in the resultant pitches) of higher amounts 
of free carbon, due to greater thermal decomposition (“ cracking ” — 
or “ pyrolysis ’’), and also lead to the formation of a very large 
number of hydrocarbons and allied substances in addition. This 
subject of the pyrogenesis of hydrocarbons has been treated fully 
by A. E. Dunstan, F. B. Thole and E. L. Lomax,™® and the reader 
is referred to the survey by those authors of the chemical problems 
involved. ) 

Coal-tar Pitch is a product of the distillation of coal tar, which 
in turn is a by-product in the manufacture of illuminating gas from 
coal, the yield of tar in such manufacture being approximately 4% 

112 


Coal-tar Pitch and Allied Pitches 113 
TABLE XXIV. 


Residuals in Pyrogenous Distillation. 





Want Partial decomposition. 
alone ** Cracking ”’ 
Raw materials used. | (‘‘ Destruc- Limited of oil 
tive dis- access of vapours. 
tillation isi air. 
Bituminous substances : Oil t 
Petroleum products . — Ww Et OE 
ater-gas tar 
EE a ee Peat tar Peat tar -- — 
DID ivacacss vncvnay sess Lignite tar | Lignite tar — — 
Pyrobituminous shales | Shale tar Shale tar — — 
| Gas-works |) Producer- | Blast- 
Bituminous coals . gas coal furnace mo 
Coke-oven fe ta 
Coal tar 
Other organic materials : 
9 ROOT ee ee eg Wood tar — oes 
BRONTE iCrineedc deers cs Bone tar — -- 





of the weight of coal carbonised. As coal, therefore, is the ultimate 
parent of coal-tar pitch, it is of interest to know something of the 
former. Stopes and Wheeler 1°° have defined coal thus: ‘‘ Ordinary 
coal is a compact stratified mass of mummified plants (which have 
in part suffered arrested decay to varying degrees of completeness), 
free from all save a very low percentage of other matter. Veins, 
partings, etc., which are found in nearly all coal are local impurities 
and are not part of the coal itself.” 

Coal is found in many parts of the world, by far the largest 
deposits (chiefly humic or so-called bituminous coal) occurring in 
the Coal Measures of the carboniferous period. The coal-forming 
vegetable materials have accumulated in a variety of ways—on 
land, in sea-water, in fresh-water, and in brackish water. Bone 15! 
has recently put forward in tentative outline a scheme indicating 
the possible formation of coal through various stages, commencing 
with the lignocelluloses, vegetable proteins and resins composing 
the original vegetable material. 

Researches by leading geologists and botanists indicate that 
coal has been formed from plants occurring in the following groups : 


Thallophyta (alge and fungi). 

Bryophyta (mosses and liverworts). 

Pteridophyta (ferns, horsetails). 

Gymnosperme (the Araucaries, Cycadaces, Ginkgoaceee). 


114 Blacks and Pitches 


Coals vary much in character, and it is found convenient to 
divide them broadly into the following groups : 1°? 


1. Brown Coals or Lignites. 

Cannel Coals. 

Bogheads or Torbanites. 
3. Humic or Bituminous Coals. 

4. Anthracite Coals. 


As we are here concerned only with a product derived ultimately 
from bituminous coals, it is sufficient to confine our attention to 
coals of this class which are black, of more or less even brightness 
and which separate into more or less rectangular pieces when broken. 

Various schemes for classification of coal on an analytical basis 
have been put forward, though none is satisfactory. But Lewes 
suggested that the coking or non-coking power of coal will depend 
upon the preponderance in the first case of resinous bodies and 
hydrocarbons, and in the second case of humus bodies and residuum 
(carbon). 

The study of the action of solvents on coal has received much 
attention in recent years, and Clark and Wheeler 1** have come to 
the conclusion that coal contained two main groups of bodies, 
‘““humous ”’ and ‘resinous”’ respectively. Jones and Wheeler 1°° 
obtained a solid paraffin, chiefly heptacosane (C,,H,,), from a bitu- 
minous coal. An investigation on the resinic constituents and 
coking properties of coal has been carried out by W. A. Bone, A. R. 
Pearson, E. Sinkinson and W. E. Stockings,45* and a number of 
important results have been recorded. 

It is evident that the coal substance can be divided into two 
main groups, viz., cellulosic (humic) and resinic, and hydrocarbon 
bodies (both saturated and unsaturated), and resinous bodies have 
been isolated, which indicates that these compounds exist in the 
free state in many types of coal. 

A comprehensive review of the present enews of the com- 
position, properties and uses of coal-tar pitch is given in a paper 
by Weiss,1°? who points out that the character of the pitch depends 
on : 


2. Sapropelic Coals 


(a) The character of the tar distilled. 
(b) The percentage of total distillate removed. 


But, as is pointed out by Butler,15® the composition of coal tar 
is so varied, and is dependent on such a variety of factors, that no 
analysis that is fairly representative can be given. This investi- 
gator further adds that coal tar varies principally as follows : 


' 


Coal-tar Pitch and Allied Pitches 115 


(1) That containing a preponderance of open chain par- 
affinoid bodies and giving a lower yield of pitch. 

(2) That characterised by the presence of closed chain 
aromatic compounds, free carbon and leading to a greater 
yield of pitch. 


The specific gravity of coal tar varies in practice between 1-070 
and 1-215, according to temperature of carbonisation and the type 
of retort used. According to Wright,!** lower specific gravity tars 
generally result when a low-carbonisation temperature (800° C.) is 
used, or if the coal be carbonised in vertical retorts, whereas high 
temperatures (1100° C.) and the employment of horizontal retorts 
lead to high gravity tars. The point of this is that the lower specific 
gravity tars are more aliphatic in character, and thus influence the 
properties of the pitch subsequently produced; such tars arise in the 
relatively new Del Monte process of distilling coal. 

The extent to which tars vary in their yield of commercial 
distillates is indicated in the following table, due to E. G. Stewart.159 


TABLE XXV. 


— Commercial Distillates from Gas Works Tar. 


Works using | Works using 


high heats | moderate heats ara on 
and light and fairly bie! ee 
charges. heavy charges. hiatal 
% % % 
| eee an 2-0 2-0 2-0 
Be GUID vive cans cyineecsdevess 1-0 6:0 5:6 
Carbolie and creosote oils 14-0 32-0 41-4 
Anthracene oil .-............ 5:0 4:0 4-0 
NS ON RD Og 78-0 56-0 47-0 
‘“* Free carbon ”’ in pitch 36-0 17-0 5:5 


Closely analogous to coal-tar pitch is coke-oven pitch from 
by-product coke ovens, used primarily for the production of coke. 
The coking is, of course, a process of destructive distillation, and 
the character of the tar, and ultimately of the pitch produced, 
depends somewhat on the type of coke oven used and the method of 
recovering the distillates. 

Lewes 153 gives the analysis of what may be considered a typical 
coke-oven tar as follows : 


116 Blacks and Pitches 


Semet-Solvay Coke Oven Tar. 


SPecific: QTAVILY” ~s..Scansasvsrscn an Merates« inet tenes 1-170 
Light dil, 80—<370" ©. gel... ssa, ewacmepnenken aes 3°7% 
Middle. oil, 170-230": C, oi...) ..s<sesahas sank da cena 9-8% 
Creosote oil, 2B0—270° Cy oo. cecsceeccecccccccecceves 12:0% 
Anthracene oil, over 270° Cy wscsscsacecetesnieenent 4:3% 
PHGOI aii ove ca cdkn. cv nccadecun aaah ets on opcaiene n 67:0% 
Water! i coves denuacsss Gigsy paadeosaearerciuts eae 2:3% 


Blast-furnace coal-tar pitch is obtained from blast-furnace tar, 
in its turn a by-product of the blast furnace when the latter uses 
bituminous coal. Generally speaking, blast-furnace pitches are 
more paraffinoid than other forms of coal-tar pitch, and owing to 
their relatively high ash content (from the flue dust) are not so 
valuable. 

By-products are recovered from the large producer-gas plants, 
of which several types are in use, and the tar is subsequently distilled 
for the production of the usual fractions. 

The problem of coal-tar distillation concerns us here only in so 
far as it relates to the production of coal-tar pitch. Several types 
of still are commonly in use, various methods of heating are employed, 
and there are both continuous and discontinuous systems of tar 
distillation in use, not only in this country but abroad. 

Amongst the commonest types of continuous-distillation plant 
in use in this country may be mentioned the systems due to Hird, 
Wilton and the Chambers and Hammond system. | 

Space forbids anything more than a brief outline of one of 
these systems, namely, the Hird continuous system, a typical 
installation of which is shown in the accompanying illustrations 
(Figs. 16-19), which, together with the following account of the 
working of the system, are taken from Warnes’s book.'*? 

Briefly, the method in the Hird continuous system is as follows. 
The crude tar is conducted from the storage tank into the regulating 
tank; from this tank it flows to the steam preheater, then to the 
first of the series of heaters, a constant head being maintained by 
means of a float valve in the regulating tank. In passing through 
these heaters the temperature of the tar is raised by its receiving 
heat from the various distillates leaving the stills as they pass 
through the coils. During its passage the tar is deprived of prac- 
tically all the contained water and the crude naphtha. The vapours 
of these materials pass into a common main, and thence through 
the tube of a coil condenser, in which they are condensed. ‘The 
condensed liquids then pass through a sight box and a separator, 
and thence to their respective receivers. 


Coal-tar Pitch and Allied Pitches 117 


After its passage through the heater-coolers the tar flows through 
the coil in the pitch cooler, and while doing this its temperature is 
further raised, whilst that of the pitch is correspondingly lowered. 
On leaving the pitch cooler the temperature of the tar may be 










—, 
| 


wi 
IAS 





ait La hh 
0 









. iW 
455 : 
oa a 
a 








teed (tif Ba 
‘ / X oe av 1 Ww) 





Fia. 16.—Plan of Hird’s Continuous Distillation Plant. 


from 120° to 200° C., according to the original composition of the 
tar. If the original water content has been high, much of the heat 
will have gone into the removal of water during the passage through 
the heaters. 

The tar is now distilled for its light oil creosotes, etc., by adjust- 
ing the heating of the stills, so that as the tar flows through them 
in succession it shows such temperatures as have previously been 


‘ea Hibs 


“qUuB[ qd UOlMel[Msiq 1B4-[V0D snonulzUoO Ss pIlH— LT “OL 








pre ae ee — 


PoE 3 
ware ee ee ee 


Dine ee, 











2S 


5 sine eet, 








118 


Coal-tar Pitch and Allied Pitches 119 


found to give desirable oil fractions. The anthracene distillation is 
helped by live steam as usual in tar distilling. 

The residue from the last still is liquid pitch, and this passes 
from the still into the pitch cooler, through which it travels on its 
way to the pitch bay, and during its progress it gives up much of 
its heat to the crude tar passing through a pipe immersed in it, on 
its way to No. 1 still. The temperature of the pitch on leaving the 
cooler is such that it practically inhibits the emission of irritating 
fumes so often observed when running off pitch in the intermittent 
systems of tar distillation. 

With such a plant it is possible to adjust the temperatures so as 
to obtain continuously uniform fractions of any desired boiling 
point, whilst at the same time the pitch can be varied to meet any 
desired twisting point. Moreover, this plant may be worked with 
a coke-oven installation (Figs. 16, 17, 18 and 19). 

Coal tar pitches show the following ranges according to Abra- 
ham : 


TABLE X XVI. 


Characteristics of Various Tar Pitches. 


Gas-works |Coke-oven| , Piast Producer- 


furnace gas 
sere ee ag coal-tar | coal-tar 
Se were pitch pitch 
(Test 1) Colourin mass... | Black Black Black Black 


(Test 2a) Homogeneity at 

PO Bie cancsis 2 Variable | Variable | Variable | Variable 
(Test 2b) Homogeneity 

when melted... | Uniform | Uniform | Uniform | Uniform 
(Test 4) Fracture ......... Conchoidal| Conchoidal| Conchoidal| Conchoidal 
(Test 7) ere gravity at 

I Ae dims caes 1-15—1-4 | 1-20—1-35] 1-2—1:3 | 1-2—1-35 
(Test 13) Odour on heating Penetrating odour characteristic of all 
coal tar pitches 

(Test 15b) Fusing point (Cube 


method) ...... 90—345° F. 
(Test 19) Fixed carbon ... | 30—45% | 20—45% | 10—30% | 20—45% 
(Test 21a) Soluble in carbon 

disulphide ...... 55—90% | 60—85% | 50—75% | 60—85% 
(Test 216) Non-mineral mat- 

ter insoluble ... | 10—45% | 15—40% | 15—35% | 15—40% 
(Test 2 lc) Mineral matter. 0—1% 0—1% 10—20% | 0—2% 
(Test 35) Sulphonation 

TOMAS .cisncses 0—5% 0—5% 5—20% 0—5% 





Carbon 90—95%, hydrogen 3—5%, sulphur 0:-5—1%, 
nitrogen 0-2—1-:2%, oxygen trace to 2%, 


LORS 1e}-[eoH snonuyzU0D 8. pPIy—'sl “OL 


2 
yi oo 
Psa -> 


? 


AMA 3 oh ate a isfy 4s Saye 
‘ . A : wee 7 





--e=--— a a ae as 


120 


‘quelq uolyeyysiq 1ey-[vop snonulzuo) 8. paly—6l “OI 


Ra 


Se as ; 
Se 
Rae SS ees 








os, 





ares 
















Coal-tar Pitch and Allied Pitches 121 


All the pitches are largely soluble in carbon disulphide, 
benzol, coal-tar distillates, carbon tetrachloride and chloroform. 
They are only partially soluble in petroleum distillates and 
turpentine. 

Concentrated nitric and. sulphuric acids char and decompose coal- 
tar pitch, though if diluted the acids effect only slow disintegration, 
whilst hydrochloric acid (concentrated or dilute) and solutions of 
the caustic alkalies and ammonia have no effect. Air and water 
appear to be without action, but the softer pitches on exposure to 
the weather gradually harden, owing to the drying out of the oily 
constituents. 

Coal-tar pitch is a complex mixture of hydrocarbons mainly 
belonging to the aromatic series, basic and non-basic nitrogen 
compounds and oxygenated compounds, all of high boiling point 
and ‘‘ free carbon ”’ (see Chap. X). According to Marcusson, coal- 
tar pitch consists of “free carbon,” high molecular weight hydro- 
carbons, coal-like resins, soluble tar bitumens, phenols, cresols and, 
in addition, three distinct tar resins respectively soluble in benzol, 
carbon disulphide and pyridine; in addition, compounds of sulphur 
and nitrogen are present. The resins are said to be aromatic 
- compounds of high molecular weight, and the one soluble in benzol 
will absorb oxygen, being thereby transformed into a mixture of 
the two other resins. On this property, so it is suggested, mainly 
depend the drying power and resinification capacity of coal-tar 
_ pitch. 

According to H. Tindale,*® coal-tar pitch can be separated into 
four constituents—oils boiling up to 300° C., “ petrolenes,”’ ‘‘ asphalt- 
enes ” and “free carbon.” In vertical retort tars, asphaltenes are 
said to occur in amounts of 25—30% and in horizontal retort tars 
to the extent of 35—40%. 

The handling of solid pitch has practnted problems consequent 
on its tendency to produce ulcerous and cancerous growths and 
inflammation of the eye,!*! and this handling is now the subject of 
Home Office regulations. Incidentally, one may remark that, being 
brittle in cold weather, fatal explosions due to coal-tar pitch have 
been recorded, as the pitch dust is more highly inflammable than 
coal dust of the same degree of fineness.1® 

According to T. Howard Butler,1®* one of the most successful 
modern methods of dealing with coal-tar pitch is to allow it while 
hot to run into pans holding approximately half a ton. When the 
pitch is cold the pans are picked up by a crane and swung into 
railway trucks. 


122 Blacks and Pitches 


REFERENCES. 


148 Statistical Department, Board of Trade, February 1925. Private 
communication to the author. 14° Journ. Inst. Pet. Tech., 1916, III, 9. 
160 “* Constitution of Coal ’’ (Monograph), Marie C. Stopes and R. V. Wheeler, 
H.M. Stationery Office, London. 1°! ‘ Brown Coals and Lignites,’? W. A. 
Bone, J. Roy. Soc. Arts, No. 3662, Jan. 26th, 1923. 15? “Coal Tar Dis- 
tillation,’? A. R. Warnes, 3rd ed., Ernest Benn, Ltd., 1923. 15% ‘‘ The Car- 
bonisation of Coal,”’ by V. B. Lewes, Ernest Benn, Ltd., London. 154 Clark 
and Wheeler, J. Chem. Soc., 1913, 108, 1704. 155 Jbid., 1914, 105, 2562. 
156 Bone, Pearson, Sinkinson and Stockings, Proc. Roy. Soc., 1922, A., 100, 
582. 157 J. Ind. Eng. Chem., 1916, 8, 841. 158 J. Soc. Chem. Ind., 1918, 
37, 23. 158¢ Journ. of Gas Lighting, 52, 169. 159 Trans. London and Southern 
District Junior Gas Assoc., 1911-1912, p. 43. 1° English Patent No. 
163,199. 191 Brit. Med. Journ., Dec. 9th, 1922. 162 Report of H.M. Chief 
Inspector of Factories and Workshops, 1914. 18 ‘‘ Modern Practices in Coal 
Tar Distillation,’ J. Soc. Chem. Ind., 1918, 237. 


Bibliography—Coal-tar Pitch and Allied Pitches. 


** Modern Gasworks Practice,’’ Alwyne Meade, London, 1921. ‘“* The 
Practical Chemistry of Coal and its Products,” A. E. Fmdley, London, 1921. 
‘“The Constituents of Coal Tar,’’ by P. E. Spielmann, London, 1924. Bone 
and Sarjant, Proc. Roy. Soc., 1919, A, 96, 119. Tideswell and Wheeler, 
J. Chem. Soc., 1919, 115, 619. Porter, U.S. Bureau of Mines, Bulletin 82, 50. 
Munro, J. Soc. Chem. Ind., 1922, 414, 1297. Bedson, Trans. Fed. Inst. Min. 
Eing., 16, Newcastle, 1899. Anderson and Henderson, J. Soc. Chem. Ind., 
1902, 21, 237. ‘‘ Researches on Coal,’ 8. Roy Illingworth, J. Soc. Chem. 
Ind., 1920, 39, 1llv and 13417. ‘‘ Ultimate Composition of British Coals,” 
T. J. Drakeley, J. Chem. Soc., 1922, 121, 211. ‘‘ The Problem of Gas Works 
Pitch Industries and Cancer,”’ John Murray, London. Thorpe, ‘“ Dictionary 
of Applied Chemistry,” Vol. III, 1922. ‘The Constitution of Coal,” W. A. 
Bone, J. Soc. Chem. Ind., 1925, 44, 2917. Distillation of Tar—English 
Patent, 224,305 of 1923. E. V. Evans, “A Study of the Destructive 
Distillation of Coal,” Gas Journ., 1924, 165, 483, 550, 629; 167, 447, 515, 580. 


CHAPTER XVI 
MISCELLANEOUS. PITCHES 


Wood-tar Pitch from Hard and Soft Woods—Wood Distillation—Rosin 
Pitch—Peat and its Distillation Products—Peat-tar and Lignite-tar 
Pitches—Water—Gas and Oil-Gas—Tar Pitches and their Properties. 


Wood-tar Pitch. 


THE treatment of wood by destructive distillation has already 
been touched upon in Chapter III, but in this chapter the volatile 
distillates will be discussed rather than the residual charcoal. During 
the period 1915—1918 wood distillation acquired considerable 
importance in this country. Several factories were erected and 
equipped with modern wood-distillation plant, only to fall into 
_ disuse and ultimately to be dismantled on the resumption of peace- 
time conditions. 

According to a report of the U.S. Department of Commerce,!* 
there were in 1923 in the United States 123 establishments engaged 
in wood distillation—77 utilising hard woods, 26 utilising soft woods, 
each with appropriate plant for recovery of the by-products, whilst 
the remaining 20 utilised different types of wood and did not recover 
the by-products. 

In the forest regions of the Continent of Europe wood distillation 
is also of great importance, and it has been computed that prior to 
1914 the yield of pure pine pitch from the distillation of resinous 
woods in the Russian forest area was about 124,000,000 lbs. annually, 
and this was largely exported from Archangel and constituted the 
Archangel or pine pitch of commerce. 

Woods may be divided into two main classes, viz : 

Hard woods—maple, birch, beech, oak, poplar, elm, willow, ash, 
chestnut. The distillation of these aims at the production of wood 
alcohol, acetate of lime, tar and charcoal. 

Resinous or Soft Woods—-pine, fir, larch, spruce, cedar. The 
distillation of these aims at the production of turpentine, wood oils, 
tar and charcoal. : 

The yield of pitch and its characteristics naturally are influenced 
by the type of wood distilled, and as a result of large-scale experi- 
ments on the destructive distillation of wood, J. C. Lawrence 1844 
finds that 


(a) Rich, soft resinous woods, like the firs and pines, yield 
about 8-4% pitch. 
(b) Lean soft woods yield 3:9% pitch. 
(c) Hard woods, like oak, birch, elm, yield about 5-2% pitch. 
123 


124 Blacks and Pitches 


Slightly different types of retorts and by-product recovery plants 
are used in distilling the two main types of wood, but in both cases 
the heavy oils or tars are fractionally distilled to yield pitch, hard 
wood yielding hardwood-tar pitch and the soft resinous woods 
yielding pine-tar pitch. 

These two classes of pitch vary somewhat in their physical 
properties, owing to initial differences in the wood and to slightly 
different types of plant used, and in duration and temperature of 
the destructive distillation of the wood. 

They comply mainly with the following characteristics, according 
to Abraham : ®° 


Hardwood-tar Pine-tar 
pitch. pitch. 

(Test 1) Colour in Mass ’.........cssnsce0s Black Brownish black 
(Test 2) Homogeneity  ......cccxceesres Uniform Uniform 
(Laat . 4) oF raceuire £4 gs oss sas caies oh dunpees Conchoidal Conchoidal 
(Test 7) Specific gravity at 77°F. ... 1-2—1-3 1-I—1-15 
(Test 15a) Fusing point (K. & 8.) ...... 100—200° F. 100—200° F. 
(Test 19) Fixed carbon ....s.0.....es0ss 15—35% 10—25% 
(Test 21a) Soluble in carbon disulphide. 30—95% 40—95% 
(Test 21c) Mineral matter .........,..00000. 0—1% 0—1% 
(Test 37) Saponifiable constituents ... 5—25% 10—40% 
(Test 37c) Resin acids  .........csccseseeens Up to 20% Up to 40% 


Wood-tar pitch consists largely of the methyl esters of the 
cresols, such as guaiacol and of the trihydric phenols, and on the latter 
probably depend its antiseptic and preservative properties. The 
pine pitches contain larger amounts of rosin acids than are found 
in the hardwood pitches. The contrasting properties of these two 
types of pitch are given by H. K. Benson and L. L. Davis.1® 

A sample of English hardwood-tar pitch examined by the author *4 
showed the following results—black colour, uniform, very brittle 
and with hackly fracture and a black streak : 


Specific gravity at 155° OC, oic..avececsasenuegunnen 1-114 

Melting point (cube method) ..........ccssscsceseees LIT, 

Freed war bon Nt fasiasasenssaasle te sacs caceeeeeeenee 16:2% 
Mineral migtter oiccsssiveris obeys edcnhasaadensaseeent arin 0:092% 
Soluble in carbon disulphide ............seeesseeeees 63:7% 

Odour On Mating i... wwc-esspahsaeckeaabegaee cee very creosotic. 


The sample was almost completely soluble in cold absolute 
alcohol. ) 

Rosin Pitch—This is somewhat similar in composition and 
properties to pine pitch. Oleo-resin, the sap of the long-leaf pine, 
is composed of turpentine and rosin, and by distillation is separated 
into these two main constituents. The rosin, in turn, is distilled 


Miscellaneous Pitches 125 


either with or without the use of superheated steam, or even in vacuo. 
If destructively distilled at atmospheric pressure, it yields about 
16% of rosin pitch and various rosin oil fractions. According to 
V. Schweizer,1** when rosin is distilled with superheated steam, 
the following yields are obtained : 


MMR TARER ANE eau ls savas vewe'nscaisvecsiuacht ne cets 5:5—5-8% 
NE ER a iehins «rundown et ied ans oben iad vhaad 11-25—12:0% 
ERA is a. ols cennipeg idcenatuanedanaenes 49:0—50:8% 
UMMMEIREOUSSS EE Cassi deta acts scenesaves¥ecsecs 10:25—10-65% 
MNT RCE cs sea0 5 5 cis DEN ad) af tas owe cs ad» Sed dees 18-0—19-:0% 


Rosin pitch is usually hard and friable, contains considerable 
quantities of resin acids (10—45%), but is free from fatty acids 
and does not weather well. 

Peat-tar Pitch.—Peat, a compressed mass from the decomposition 
of vegetable matter in a swampy environment, consists of a mixture 
of water, iron and calcium salts, vegetable fibres and humus acids 
and small amounts of nitrogenous and sulphur compounds. By 
many it is considered as the precursor of lignite in that chain of 
metamorphic changes which, commencing with the cellulose of 
woody fibre, leads ultimately to coals. The great obstacle to its 
commercial exploitation has always been the difficulty of satis- 
factorily dehydrating it and the process known as ‘“‘ wet carbonising ”’ 
has offered the greatest possibilities. Now that the main difficulties 
inherent in its utilisation are said to be overcome by the proposals 
of W. Wieland,*®’ its use should become more general. 

Dry briquetted peat is distilled to a limited extent by a variety 
of methods, and yields gas, tar, ammonium compounds and a coke 
hard enough to be used in blast furnaces. The tar, a black, viscid 
liquid, is produced to the extent of about 9—10% of the air-dried 
peat, and on distillation dry peat tar yields the following, according 
to Abraham : 


TABLE XXVII. 
Distillation Products from Peat. 


After 
Sends, Purification. 
YN % 
MNO SE Eso Sc pide hse bav's vnc dus’ ong aig 16 12 
PY MAID oii v sects tcc censanveses 30 25 
TAIL OE cscs» sigs sv dah hie > wsaans 15 13 
MORNE IES, ~ on chins Sevaiccaessiediandaceubs 12 2 
MMROMEL DOI a pe kneccinonssxnngseaararessh x 16 16 
MAL Lia, Gates > .abkuAsibds She asende»toernike = 12 


(as a ERR i a RR eg ree 11 20 


126 Blacks and Pitches 


EK. Bornstein and F. Bernstein 1°° devised a process for the 
destructive distillation of crude peat, and the resulting tar, when 
dehydrated, yielded 47% of a paraffinoid pitch. According to 
G. T. Morgan and C. E. Scharff,1®* the redistillation of peat tar 
yields about 5:8% of a typical soft pitch with asphaltic properties. 

Ordinarily peat-tar pitch has much the same properties as 
lignite-tar pitch, and has poor weathering properties. 

Lngnite-tar Pitch—Brown coals (Lignites), cannel coals and 
bituminous shales all yield tars on destructive distillation, and these 
tars subsequently give rise to pitch, allied on the one hand somewhat 
to coal-tar pitch and on the other hand to wood-tar pitch. 

Large deposits of lignite occur in the U.S.A., in Canada, to some 
extent in Australia, one small deposit at Lowe, in Derbyshire and 
in Germany. In the last-mentioned country low-temperature 
retorting 17° is resorted to in considerable extent. 

Retort lignite is treated in one or two ways, thus : 


1. Low-temperature destructive distillation. 
2. Solvent extraction for the removal of montan wax and 
destructive distillation of the residue. 


In the case of distillation, this takes place between 270° and 
500° C., and the yield of tar is about 5—10% of the lignite distilled. 
The tar, which is of buttery consistency at the ordinary temperature, 
is dark brown to black in colour; and is composed of liquid and 
solid members of the paraffin and olefine series of hydrocarbons, . 
together with small amounts of hydrocarbons of the benzol series 
and higher phenols and their derivatives (see Chapter X). There 
are also present about 10—25% of solid paraffin and 0:5—1:5% _ 
of sulphur. Asphaltic substances, however, according to Mar- 
cusson, are scarcely present. 

The tar is fractionated into crude oil (33%), a paraffinoid dis- 
tillate (60%), small amounts of other distillates and about 5% of 
lignite-tar pitch, or it may be continued to the stage of coke. 

Lignite-tar pitch is characterised by the presence of phenols, 
the absence of insoluble carbonaceous matter, the presence of small 
amounts of paraffin wax, and almost complete solubility in benzol; 
these characters serve to distinguish it from coal-tar pitch. From 
wood-tar pitch it is distinguished by its content of sulphur and 
paraffin, and from asphalt and resin pitch by the diazo-reaction 
indicating the presence of phenols. 

In the following table E. Graefe 1° has indicated the differences 
between lignite-tar pitch and many other residual pitches, thus : 


Miscellaneous Pitches 127 
TABLE XXVIII. 


Comparison of some Residual Pitches. 


Residue ; 
after Sulphur. Todine 
benzol value. 

extraction 
Lignite goudron , 66-5 
TE EMRE Che 69 pie. sovcses. « . 93°7 
i, a cacue re . “§ 50-0 
NRT gi dnc sguccvevescce . . 140-0 
Petroleum pitch I : 49-4 
a re ii . : 70:3 
a ee aL . 103-5 





In Germany, by reason of its solubility in petroleum distillates, 
lignite-tar pitch finds extensive use in the manufacture of cheap paints. 

The retorting of bituminous shales is also a source of shale tar 
and shale-tar pitch in many parts of the world, not only in the U.S.A., 
but in Australia, Germany and Scotland. Shale tar and the resulting 
pitch are more paraffinoid than asphaltic in character, and generally 
are closely similar in properties and composition to the corresponding 
products from lignite. 


Water-gas and Oul-gas Tar Pitches. 

These and their corresponding tars are allied on the one hand 
to petroleum asphalts, and on the other to coal-tar pitch. In 
modern water-gas plant, anthracite coal or coke undergoes partial 
combustion and is then subjected to the action of steam, leading 
to the production of “blue gas,” : C+ H,O=CO+H,. This 
gaseous mixture is mingled with gas-oil and the resulting mixture 
passed through a superheater at 650—700°C., to crack the oil 
vapours. In this way a certain amount of tarry formation occurs, 
and below are given analyses of some of these tars. 


TABLE XXIX. 


Water-gas Tars.\74 





128 Blacks and Pitches 


Oil-gas tars arise in the cracking or heating of petroleum alone 
in closed retorts, some 10% of tar being recovered in one of the 
processes employed. 

Water-gas tar and oil-gas.tar, when suitably dehydrated, are 
distilled by similar methods to those employed with coal-gas -tar, 
yielding corresponding pitches, which resemble coal-tar pitch, from 
which they differ in containing paraffin to a certain extent and in 
their low content of “free carbon”? (2—15%), 7.e., non-mineral 
matter, insoluble in carbon disulphide. 


REFERENCES. 


164 Ind. Hing. Chem., Feb. 20th, 1925. 147 J. Soc. Chem. Ind., 1918, 37, 7. 
165 J, Ind. Eng. Chem., 1917, 9, 141. 18® “The Distillation of Resins,” 
2nd Edn., 1917, Scott, Greenwood & Son. 157 Chem. Zett., 1912, 36, 
1305. 158 J. Gas Lighting, 1915, 129, 731. 19° Hconomic Proc. Roy. 
Dublin Soc., 1915, II, 161. 17° Daniel Bellet, Rev. gen. Sct., 1917, 28, 118. 
171 L. Schmitz, ‘‘ Die Flussugen Brennstoffe,” 1912. 


Bibliography. 

A. C. Craig, A. E. Dunstan, F. M. Perkin and A. G. V. Berry, J. Inst. 
Pet. Tech., 1918, 4.  ‘‘ Die Braunkohlenteer Industrie,” Edw. Graffe, 
1906... The Brown Coal Distillation Industry of Germany,” D. R. Steuart, 
J. Soc. Chem. Ind., 1917, 36, 167. ‘‘ Shale Oils and Tars,’’ Scheithauer. 
Hs i ea J. Inst. Pet. Tech., 1916, 2, 162. W. Dominick, Petroleum, 
1924, 20, 1891. 


CHAPTER XVII 
FATTY ACID PITCHES 


Subdivided into Stearine Pitch, Cotton-seed Pitch and Wool Pitch—Saponi- 
fication of Fatty Oils—Cotton Black Grease and Wool Grease—Dis- 
tillation Plant and its Operation—Characteristics of Various Stearine, 
Cotton and Wool Pitches—Bone-tar Pitch. 


A GREAT variety of names has been used to designate the product 
Fatty-Acid Pitch, thus: ‘“ Fettpech”’ (German), ‘‘ Kerzenteer ”’ 
(German), goudron (French), candle pitch, cholesterol pitch, fat 
pitch, stearine pitch and many others. 

It may be stated generally that all the fat pitches are residues 
remaining after the distillation of fatty matter in superheated 
steam, whether aided or unaided by diminished pressure. 

The present author prefers the following subdivisions : 


(a) Stearine Pitches resulting from the distillation of fatty 
acids produced by saponification of the familiar glyceride- 
containing fatty oils, such as tallow, palm oil, palm kernel oil, 
whale oil, etc. 

(b) Cotton-seed Pitch, which is the residue after distillation 
of cotton black grease. 

(c) Wool Pitch, which remains after distillation of wool 
grease or Yorkshire grease, this grease being chemically a 
wax, and not a glyceride. 


The first important reference to stearine pitch is in a paper by 
E. Donath and R. Strasser,1”2 who mention that in the distillation 
of fatty acids used in candle manufacture, 2—7°% of tarry matter 
remains in the still, and that on redistillation of this residue with 
superheated steam at 300°C. a black asphaltic mass of stearine 
pitch remains. It further appears that this pitch was used at 
Roubaix in the production of an oil gas. 

(a) Stearine Pitches.—The raw material concerned in the manu- 
facture of these pitches is the mixed higher fatty acids produced from 
fatty oils by saponification, and it is necessary to digress briefly here. 

Our ordered knowledge of the subject of saponification was 
advanced when the constitution of fatty oils was established by the 
researches of Chevreul,!”4 Berthelot,175 and Wurtz,!7* when it was 
shown that these oils consist mainly of the triglycerides of the 
fatty acids. 

The triglycerides may be represented by the general formula 


CH,—OR /OR 
H—OR or (,H,COR 
CH,—OR OR 


9 129 


130 Blacks and Pitches 


where “R” represents any fatty acid radical, usually the radical 
of a higher fatty acid (see Chapter X). 

Following the work of the early pioneers, the change which 
occurs when a fatty oil is boiled with a solution of a strong base 
such as caustic soda may be expressed by the formula 


CH, OR NaOH CH, OH 
CHO R + NaOH = CH + 3NaOR 
CH 20R NaOH CH, OH 


where R is the acid radical of any higher fatty acid, and for sim- 
plicity’s sake the acid radical is supposed the same throughout. 

The study of the hydrolysis or saponification of fatty oils has 
been carried on largely by Geitel,1?* 178 Lewkowitsch,1” 18° Mar- 
cusson 181 and others to the conclusion that this hydrolysis is stage- 
wise and may be indicated thus : 


Triglyceride —-> diglyceride —-> monoglyceride —-> glycerol + fatty acids. 


These reactions are interdependent, the rate of formation of the 
glycerol being conditioned by the rate of formation of the mono- 
glyceride and so forth, the whole operation consisting of three simul- 
taneous bimolecular reactions taking place in the same system, but 
not necessarily at the same rate, the older view of a quadrimolecular, 
direct action being regarded now as untenable. The present author 
has given elsewhere 1°? a full résumé of the investigations of this 
aspect of the subject. The demarcation into stages cannot be 
observed on a technical scale, partly because it is impossible to 
isolate or separately demonstrate the existence of the intermediate 
products of the stagewise hydrolysis. 

Theoretical considerations show that water or steam is essential 
to saponification, but its use alone makes the completion of the 
reaction almost impossible on a technical scale, and in consequence — 
various means have been introduced to hasten the reaction, and in 
modern industrial practice resolve themselves into : 


1. The acid process, in which fats are boiled with concentrated — 
sulphuric acid. 

2. The Twitchell process, use being made of aromatic oleo- 
sulphonic acids. 

3. The autoclave process, in which the fats are heated in 
contact with high-pressure steam in the presence of small 
amounts of alkaline-earths such as lime, magnesia, etc. 

4. The fermentation process, which depends on the lipolytic 

» action of certain enzymes, such, for instance, as that in the 
castor seed. 


Fatty Acid Pitches 131 


The technique of the foregoing processes need not be described 
here, but the reader is referred to the publications of Lewkowitsch 18° 
and to a résumé by the present author contained elsewhere.18? 

Much of the early work on saponification concerned itself mainly 
with the chemical aspect of the subject, but in recent years the 
extension of our knowledge in relation to surface tension effects, 
colloidal phenomena, and the importance of emulsification and the 
part that these play in many familiar industrial operations, indicate 
that physical considerations may outweigh purely chemical ones 
when dealing with a heterogeneous system such as exists in the 
emulsion of fatty oil and aqueous alkaline or acid solution, which 
constitutes the reaction mixture in industrial saponification. 

The function of the particular reagents, used technically in the 
various industrial methods of saponification already enumerated, 
becomes that of effecting intimate association of the reactants, 
and the accumulated evidence indicates that this association is best 
achieved by emulsification. The author has recently summarised 
the current views relative to the physical aspect of saponification.184 

In the acid process of saponification usually applied in the case 
of tallows and palm oil and similar fats, a change takes place in the 
reaction, leading to the production of y-stearolactone, 

CH,;(CH,),3;°CHCH,CH,CO, 
Ose ea 
CH; (CH,),;CH—CH,(CH,),COOH 
OH 
this is of importance in the subsequent distillation.1®° 

The distillation of the fatty acids is carried out by means 
plant of the type shown in Fig. 20. In this particular plant the 
still is of cast iron, 7 ft. in diameter and 7 ft. in depth from the 
top joint of the still, the body of which is cast in one piece, on 
to which is bolted a cast-iron cover, the whole being supported as 
shown. The contents of the still are heated by superheated steam 
by means of an internal steam coil. The principal fittings include 
a draw-off cock, feed valve, steam valve, safety valve and a self- 
recording thermometer, enabling the temperature of the still contents 
to be noted during the progress of the operations. The fatty acids 
are distilled in steam, and for this purpose an open steam coil 
through which passes superheated steam is passed into the still. 

The cover is surmounted by a copper head with a copper vapour 
outlet connected to the condenser, which is a series- of air-cooled 
vertical copper pipes, as indicated in the diagram. Each pair of 
tubes is provided with a bottom outlet separately connected to a 
copper worm condenser in a water-cooled worm tank, with suitable 





and i-hydroxy-stearic acid, and 


132 Blacks and Pitches 


outlets for the various distillates. The end of the condenser passes 
to a water-sealed fume-absorbing condenser or gas pan, of the 
cascade type, with water inlet valve and vapour vent pipe open to — 
the atmosphere at the top. The still shown is arranged with a 
tubular feed heater, heated by means of the exhaust steam from the 
heating coil in the still. 

Stills of similar design are in use for direct fire heat, the stills 
being then appropriately set in fire-brick with a suitably built flue, 
which carries the hot gases round the outside of the bottom of the 
still. Suitable setting of the still in the brickwork is of importance, 
so as to ensure the bottom of the still, rather than the higher parts 
of it, getting the bulk of the heating effect of the hot flue gases. 
When direct fire heat is used, it is necessary that a long cast-iron 
outlet pipe to carry away the pitch be cast solid with the body. 

In an actual distillation the best practice is to work with steam 
of high superheat and a low pressure of about 5 to 8 lbs./sq. inch; 
the fatty acids distil over in the steam and are condensed in the series 
of air-cooled condenser pipes, and run away to collecting pails, 
arranged under the worm condenser, whilst the steam, together 
with any uncondensed lower fatty acids, and such products as carbon 
monoxide, carbon dioxide, acrolein and uncondensable hydro- 
carbons—the products of decomposition and pyrolysis in the still— 
pass away to the cascade condenser. 

The aim of the distiller is to recover as much fatty acids from 
the still as possible, and thus reduce to a minimum the yield of 
pitch. The amount of recovery is determined somewhat by the 
nature of the material distilled, the extent to which the original 
fatty oil was saponified and the extent to which the distillation is 
carried. For fatty acids, testing up to 95—98% acidity (as oleic — 
acid), the yield of pitch is lower than for fatty acids testing only 
90% acidity. The longer the distillation is continued the less the 
yield of pitch and the less saponifiable matters such pitch will 
contain and the harder its consistency. 

The author records hereunder the results of some actual large- 
scale distillations carried out under his control : 


Acidity (as Average 
Autoclaved fatty acids from oleic acid) yield of 
of autoclaved pitch. 
material 
: of 
Oo 0 
Tallow (English beef) — ................06 96-3 3-7 
Palan oil (Niger). cctsskescpeexnepstearesect 94:5 3°8 
Whale ou (NOS) iscssasiess yb cee wed ten 94—96-2 8—9 


Fish oil (J Bpan) 6.5.2. Se eer 90—92 10—12 


(‘F O°" ‘uopuoyy ‘oueyT ooyg “pF ‘gp “py ‘sueoyg pue suog yyouueg Ag) 
‘quel UoHyeyysig ploy AWeq— 0s “OLA 






























































































































































Fatty Acid Pitches 


133 


Characteristics of some stearine pitches from whale oil fatty 


acids examined by the author.*4 


Sample A Sample B. 
(Test 1) Colour in mass ............ Black Black 
(Test 2) Homogeneity ............ Uniform Uniform 
OeeeG 2)  PLAOUITG . 2.660... ks eee e sees None—sticky Brittle 
ee ENAMEL 1 hii Si vvecidincecsees Bright Bright 
(Test 7) Specific gravity ............ 1:016 @ 15:5° C. 1-046 @ 15-5° C, 
(Test 15) Melting point (drop 
SEENON) Woks eveiices. 37:9° C. 68-5° C, 
(Test 21a) Solubility in CS, ......... 97-:1% 90-9° 
(Test 21c) Mineral matter ............ 0:-48% 7-23% 
MONS iach eaneViw tense ens TTAL% 73:19% 
En Ro ee 10-35% 10-49% 
Oxygen (by difference) . 12:06% 9:09% 
ROUONS. PS eae eiea cs vias trace al 
OE eee nil gs 
(Test 37d) Saponification value 67:8 104 
F.F.A. (as oleic acid) 10:7% 5:41% 
(Test 44) iodine OL a 126 97-9 


Characteristics of some stearine pitches from palm oil fatty 


acids examined by the author ; *4 


Sample A. Sample B. 
(Test 1) Colour in mass ............ Black Black 
(Test 2) Homogeneity _............ Variable Uniform 
Pe PA OUULG Fy psocednenscdveccieee None—pliable Fairly brittle 


RTT ENISUIO  cssechescensascessees 
(Test 7) Specific gravity .......... 
(Test 15) Melting point (drop 


Dull 


0:982 @ 15-5° C. 


Bright 
1-060 @ 15:5° C. 


WOOUNOG) -. cissiveevass 43° C. 60-7° C 
(Test 21a) Solubility in CS, ......... 94-62% 93-7% 
(Test 21c) Mineral matter ............ 2°98% 33% 
Oe eee 79-6% 76-80% 
I VOPOM ON Seu ceccesscasenes 11-26% 9-289 
Oxygen (by difference) 6-16% 10-62% 
Sulphee eee ke ect ie Skies ail nit 
(Test 37d) ee en value 58-3 93-4 
A. (as oleic acid) 8-7% T4% 
(Test 44) Iodine DRPMAALES chen pry nos’ en's é 118-5 94°3 


(b) Cotton-seed Pitch.—Vegetable oils intended for edible purposes 
require to be refined in order to remove free fatty acids, suspended 
impurities and albuminous matter, colouring matter, and the 
resinous fatty unsaponifiable matter always found with the crude 
oil, and cotton oil is of particular interest in this connection. Crude 
cotton oil as obtained from the seed by crushing varies in colour 
from reddish-brown almost to black, the latter colour being that of 
Bombay cotton oil as ordinarily produced in English oil mills. 

The first stage in the refining of this cotton oil is to heat it in 
large tanks tapering downwards to a cone piece at the bottom, the 
tanks being provided with suitable stirring gear and heating coils. 
Caustic soda solution of specific gravity about 1-125 is slowly run 


134 Blacks and Pitches 


through sprinkler pipes on to the heated agitated oil, with the result 
that combination takes place between the free fatty acids in the 
oil and the caustic soda, and ultimately soap separates out. On 
completion of the neutralisation and with cessation of the agitation 
the soap collects at the bottom of the tank, leaving clear bright 
neutral cotton oil at the top. The material which separates out is 
known as Cotton-seed Mucilage or Cotton Soap-Stock, and its 
composition is 30—40% cotton oil, 50—60% cotton fatty acids in 
the form of their soaps, traces of water, free caustic soda, albuminous 
matter and colouring matters. 

Usually the cotton-seed mucilage is acidified with hot dilute 
sulphuric acid, and as a result a black grease, Cotton Black Grease, 
is thrown to the surface. This Cotton Black Grease, after settling, 
consists approximately of about 30° neutral cotton oil, 60% cotton 
fatty acids, albuminous matter, black colouring matter, fatty 
unsaponifiable matter and traces of water. It is sold to the dis- 
tillers on the basis of 98% fatty matter soluble in carbon disulphide. 
Sometimes the separated black grease is saponified by one or other 
of the usual methods to which reference has already been made, 
in order to break up the neutral oil. A better method of achieving 
this end is to saponify the Cotton-seed Mucilage first before proceed- 
ing to the conversion into black grease. 

Ultimately the cotton black grease is subjected to steam dis- 
tillation, the same plant and procedure being adopted as that 
described in connection with fatty acids, with the result that light- 
coloured distilled cotton fatty acids pass over and a residue of 
Cotton Pitch or Cotton-seed Pitch or Cotton Stearine Pitch remains. 
The yield of pitch averages 10—20% of the weight of black grease 
distilled, representing 1—2% by weight of the original cotton-seed 
oil before neutralisation. The lower the percentage of neutral oil 
in the black grease, the smaller will be the yield of pitch, for on 
distillation the neutral oil does not always split to yield fatty acids 
which distil over in the steam, but a certain amount of breaking up 
into hydrocarbons and condensation products occurs, and these 
products remain in the pitch. 

Cotton-seed pitch is usually produced in three grades: hard 
and brittle, rubbery, and soft, is usually black, uniform to variable 
in homogeneity, with a fracture varying from nil to conchoidal 
and testing generally within the following limits : 


(Test 7) Specific gravity at 15-5° C. ............ 0-90—1-20 

(Test 15) Melting point (drop method) ......... Variable 

(Test 21c) Mineral matter — ..i.fiinseccsenenssenens 2—5% 

(Dest 28) “Subpiens 20 ore ond tex one voad aotee aeeemaiaee Maybe up to 1% 
(Test 37a) Acidity (as oleic acid) .........c..eeeeee 2—50% 


(Test 37d) Saponification value (usually) ...... 80—120 


Fatty Acid Pitches 135 


(c) Wool Pitch Wool grease is the oily material naturally occur- 
ring in sheep’s wool and is extracted from the wool clip when this is 
suitably boiled with an alkaline soap solution and subsequently 
acidifying the liquor, whereby the grease is caused to rise to the top, 
and after removal, and appropriate purification and dehydration, 
it is obtained as a light to dark-brown grease of m. p. 30—40° C. 

Chemically wool grease is an animal wax and consists of esters 
of the higher monohydric alcohols and higher monobasic fatty 
acids (see Chapter X), such as cetyl palmitate, C,,H,,CO-OC,,H,, 
(the ester of cetyl alcohol and palmitic acid), a certain amount of 
free higher fatty acids, and considerable amounts of unsaponifiable 
matter, the latter consisting of higher monohydric alcohols and 
cholesterol. Normally glycerides are not constituents of wool 
grease. 

Wool grease is recovered in great quantity in the woollen centres 
of the West Riding of Yorkshire, where many of the Municipal 
Sewage Works have installed special plant for the recovery of the 
grease from the industrial effluent. This grease is subjected to 
steam distillation, without previous saponification, the same type 
of plant being utilised as for the distillation of fatty acids. 

A number of typical samples of Yorkshire wool grease tested 
in the author’s laboratory showed the following results : 


TABLE XXX. 


Analyses of Wool Greases. 





Inorganic Unsaponi-| Saponi- Acid. Todine 
matter. Water. fiable fication value. value. 
matter. value. 
% % % 

| ee 1-4 0-82 39-65 101:3 55-5 25-73 

i: Seren 1:77 0-89 43:5 121-7 66:9 29-5 
Gas. 0-6 0-75 29-3 131-4 69-3 26:48 
Dee. 0-44. 2-1 36-6 135 70-2 27-1. 


According to G. F. Pickering,!°® wool pitch has the following 
characteristics : 


Soft to hard, dark brown to black, usually bright and of 
uniform consistency, specific gravity at 15-5°C., 0-97—1-0, 
melting point 90—160° F., ash 0-5—5:5%, saponifiable matter 
about 7% in hard pitches to 30% in softer samples. 

Free fatty acids 0:75—15%, with 6% as an average, iodine 
value 35—45, 


136 Blacks and Pitches 


The various fatty-acid pitches (stearine, cotton and wool pitches) 
vary somewhat in their chemical and physical properties, due to 
differences in the materials from which they are made. According 
to the method employed in the preparation of the fatty acids, 
these bodies contain, in addition to the saturated and unsaturated 
fatty acids, small amounts of neutral fats, hydroxy-acids, anhydrides 
and lactones, fatty unsaponifiable matter and colouring matter. 
In the case of cotton black grease all the foregoing may be present, 
with the addition of albuminous matter and a larger percentage of 
neutral fats than found with the fatty acids. Wool grease, of 
course, contains no glycerides, but considerable amounts of higher 
alcohols and some cholesterol. | 

During distillation of these raw materials saturated fatty acids 
generally distil away first, but some of the unsaturated acids, such 
as oleic and those of higher unsaturation, are partly polymerised 
and partly suffer decomposition, being transformed into saturated 
and unsaturated hydrocarbons of the naphthene type (see Chapter X). 

Some portion of the i-hydroxy stearic acid present in the fatty 
acids (when the acid process of saponification has been bai under- 
goes change thus to iso-oleic acid : 


ag eres Mc tree —_> 
ati ne stearic acid 
CH,;(CH,),—CH(CH,),COOH + H,O 
iso-oleic acid 
(a solid isomer of oleic acid) 

Condensations and intramolecular changes between some of the 
components in the still may also take place, and there is also a 
certain amount of cracking (pyrolysis), leading to the production 
of hydrocarbons, not only from the fatty acids and neutral fats, 
but (in the case of wool grease) also from the higher alcohols and 
cholesterol. : 

These pitches, therefore, may be regarded as complex mixtures of 
saturated and unsaturated fatty acids and condensed fatty acids, 
saturated and unsaturated hydrocarbons, some neutral fat, 
anhydrides and lactones, and in the case of wool pitch, cholesterol 
and the higher alcohols. 

In view of the contrasting features of the several conflicting 
theories accounting for the genesis of. petroleum and the asphalts, 
a detailed examination of the fatty acid pitches is of scientific 
interest and importance from the point of view of the possible 
formation of petroleum from animal matter and fish blubber. 


Fatty Acid Pitches 137 


All fatty acid pitches are converted into more or less infusible 
and insoluble and somewhat elastic masses on exposure to the 
atmosphere for long periods or even by heating to about 350° C. 
out of contact with the air. A sample of medium-soft pitch from 
whale oil fatty acids left exposed by the author *4 for two months in a 
porcelain dish in the laboratory formed a tough, difficultly soluble 
skin on its surface. The iodine value, originally 123-8, diminished 
to 102:5 in the case of the surface skin formed. The weather- 
resistant properties of these pitches, due to the saponifiable matter 
they contain, makes them specially of value in the manufacture of 
certain japans and varnishes and in the production of certain 
- waterproofing materials. 

Bone-tar Piich—In the dry distillation of degreased bones 
(mentioned in Chapter IIT) a distillate, known as bone oil, bone tar, 
Dippel’s oil, is produced as a by-product to the extent of 10—25% 
by weight of the bones. Fractional distillation of this tar yields 
Bone Pitch to the extent of about 23% of the tar. This pitch is 
somewhat intermediate in its properties between asphalts and 
fatty acid pitches. It is usually a hard, jet-black, very bright solid 
with a conchoidal fracture with m. p. about 100°C. It usually 
contains small amounts of sulphur, derived doubtless from ne 
albumen in the bones from which it originates. 


REFERENCES. 


172 Chem. Ztg., 1893, 17, 1788. 4174 Chevreul, ‘‘ Récherches chimiques sur 
‘les corps gras d’origine animale,’’ Paris, 1815-1823. 175 Berthelot, ‘« Chimie 
organique fondée sur la synthése,’’ Paris, 1860. 17° Wurtz, ‘‘ History of 
_ Chemical Theory.” 177. 178 Geitel, J. prakt. Chem., 1897, 55, 429; 1898, 
57, 113. 179% 180 Lewkowitsch, Proc. Chem. Soc., 1899, 190; Ber., 1900, 89. 
181 Marcusson, Zeit. angew. Chem., 1913, 26, 173. 182 H. M. Langton, 
Journ. Oil and Colour Chem. Assoc. y 1922, 29, 41. 183 “ Technology and 
Analysis of Oils, Fats, and Waxes,” 1923. 184 Hf. M. Langton, J. Soc. Chem. 
Ind., 1923, 42, 517. 185 J. Lewkowitsch, J. Soc. Chem. Ind., 1897, 392. 


Bibliography—Fatty Acid Pitches. 

D. Holde and J. Marcusson, Mitt. kénigl. techn. versuchamt, 18, [3], 147. 
Kassler, Chem. Rev. Fett-Harz-Ind., 1902, 9, 49. D. Wesson, J. Soc. Chem. 
Ind., 1907, 26, 595. E. Donath, Chem. Rev. Fett-Harz-Ind., 1905, 12, 42 
and 73. E. Donath and B. M. Margosches, Chem. Revue, 1904, 194. 
*Stearin Pitch,’ H. Meyer, Seif. Zeit., 1914, 44, 394. ‘‘ Distinguishing 
between Petroleum Residuums and the Various Fat Pitches,’? A. R. Lukens, 
The Ohemist Analyst, 1917, 20, 3. ‘‘ Fatty Acid Distillation Plants,”’ 
O. H. Wurster, Chem. and Met. Hng., 1921, 25, 651—656. 


CHAPTER XVIII 


THE WEATHERING AND AGEING OF BITUMINOUS 
MATERIALS 


Effects of Exposure to Air, Sunlight and Moisture—The Light Sensitiveness 
of Asphalt. 


THE principal uses of bituminous materials, both natural and 
artificial, are in the manufacture of bituminous fabrics such as 
roofing felt, the waterproofing of damp courses, in electric insulation, 
in the manufacture of paints, varnishes, japans, in roadway and 
pavement construction and in a variety of other ways closely allied 
to the foregoing modes of employment. All these varied usages 
involve exposure in a greater or lesser degree to the action of moisture, 
sunlight and air, and comprised in what is termed weathering. 
This exposure involves changes, which may be negligible or im- 
portant, in the physical and chemical condition of the bituminous 
substances. 

M. Toch 18° noted that some petroleum asphalts are unsuitable 
for making bituminous paints, and he has cited as an example a pure 
petroleum residual asphalt which, applied in a good continuous coat 
on cast-iron pipes in a cellar, lasted 3—4 years, whereas on the roof 
of a building exposed to direct sunlight the petroleum asphalt 
underwent complete decomposition in 20 days, with the liberation 
of “free carbon.” His experiments indicated that this action was 
inhibited by incorporating an opaque pigment. Moreover, fatty 
oils (containing the triglycerides) are not affected in this manner 
and retard the disintegration of petroleum asphalts when blended 
with them. 

Investigations of the weathering of bituminous substances have 
been conducted by P. Hubbard and C. S. Reeve,18? by 8S. R. Church 
and J. M. Weiss,18° by C. S. Reeve and B. A. Anderton 1®° and by 
C. 8. Reeve and R. H. Lewis. The changes may be of a com- 
plicated character, being the cumulative effect of one or more of 
the following reactions. 

Evaporation.—The more volatile constituents on exposure to 
air and the sun’s rays are gradually lost. The tars particularly 
are liable to loss in this way, and the softer pitches harden owing 
to the evaporation of the more oily constituents, and usually the 
higher the temperature the greater the volatilisation. 

Oxidation.—Exposure to the air brings this about more rapidly 
as a rule at high than at low temperature, and the action is two-fold, 
involving on the one hand direct union between oxygen and the 
bituminous substance, and on the other hand elimination of a 

138 


The Weathering and Ageing of Bituminous Materials 139 


portion of the hydrogen in the form of water, and the conversion 
ef the hydrocarbons in the bituminous substance to hydrocarbons 
of a lower degree of saturation, thus: 2C;H, + O, —> 2C,H,-, + 
2H,0, . ° 

Carbonisation.—This really represents carrying to the stage of 
completion the oxidation of hydrogen and the consequent formation 
of “‘free carbon” in the bituminous substance; the reaction is 
most rapid in the presence of sunlight. Scrapings from a bitu- 
minous surface which has undergone such carbonisation are found 
to consist largely of fine particles of carbon. 

Polymerisation.—This is due to a condensation or polymerisation 
of the molecules, and is shown by a hardening or setting of the 
bituminous substance. This takes place to a greater or lesser 
extent on heating bituminous substances; particularly is this 
the case with fatty acid pitches, and the more glycerides and the 
less fatty acids they contain, the more does this setting to a hard 
infusible mass take place. 

Effects of Moisture.—The action of moisture may be two-fold— 
actual absorption of water and a gradual washing out of soluble 
constituents. Generally, though, this factor—the action of moisture 
—is less far-reaching than the previously enumerated factors. 

Many of the harder naturally occurring asphalts suffer no change 
due to ageing or weathering, but we have seen that in the case of 
Trinidad lake asphalt a rapid hardening at the surface of the lake 
takes place. A hardening takes place also at the exposed surface 
of many petroleum residual asphalts, and in the case of many residual 
pitches. In an extended experience of fatty acid pitches derived 
from a variety of raw materials the author has observed how these 
on exposure become dulled and hardened at the surface, due to the 
action of light and air, and actual analyses revealed in these cases 
a decrease in the iodine value and an increase in the oxygen content 
of the fatty pitch. 

According to P. E. Spielmann,®*" the change occurring in the 
case of many residual bitumens is twofold and involves a slow 
surface hardening, due to the action of light and air on the residual 
oils remaining in the bitumen, and a slower “ settling down.’ He 
makes the tentative suggestion that this latter phenomenon is due 
to “internal molecular rearrangement,’ and in support of this 
view quotes the determinations given in the table at top of p. 140, 
which were obtained on a sample of residual bitumen. 

The increases in asphaltene content and in fusing point are con- 
sidered to support the theory of “‘ internal molecular rearrangement.” 


140 Blacks and Pitches 


Penetration of Ageing Residual Bitumen. 





Time in At surface. 3 mm. below Asphaltenes. 
days. surface. 
0 46 a 315% 56-0 
7 42 45 — — 
43 38 (35—41) 43 (41—44) é eee 
205 25 (20—30) 39 (36—42) ag ga 
487 23 (21—26) 33 (30—40) 38-9% 58-3 


Spielmann®** also advances the view that the immediate surface 
hardening—besides being due to oxidation, the action of light and 
polymerisation—may be correlated with the presence of paraffin 
wax or ceresine in the bitumen. 

Summarising, it appears that weathering and ageing affect 
bituminous substances by making their colour lighter, destroying 
their homogeneity by the formation of free carbon and dulling the 
surface. ‘There is usually an increase in the specific gravity, hard- 
ness, viscosity, melting point, flash point, and decreases in the 
case of the amount of volatile matter, solubility in carbon disulphide 
and 88° petroleum naphtha. The amount of saponifiable consti- 
tuents remains unchanged. Such physical properties as ductility, 
tensile strength and adhesiveness also undergo diminution. 

The sensitiveness of bituminous materials to light, regarding 
the matter largely from a physical aspect, may be considered in 
this chapter. This light-sensitiveness of bitumen has been known 
since the time of J. N. Niepce, who in 1824 produced a portrait 
as a result of experiments with a solution of “ asphalt,” and the 
_ property has been made use of in a number of photo-mechanical 
processes. More recently the study of the subject has been revived. 
Maderna,!® for example, has found that different portions of a 
bituminous complex possess a light-sensitiveness differing in magni- 
tude, though in each case of the same quality, and Paul Gédrich 1% 
found that petroleum asphalts free from paraffins are, relatively 
to other asphalts, the most sensitive towards light. 

J. Errera 1% has made a careful study of the light sensitiveness 
of Judean asphalt and in this connection classifies its constituents 
into a-, B-, y-resins, the last-named being sensitive to light and 
existing in the colloidal condition, the asphalt as a whole being 
both molecularly and colloidally dispersed. Whatever be the 
underlying cause of this light sensitiveness, it appears to be estab- 
lished that it is intimately associated with colloidal phenomena. 


The Weathering and Ageing of Bituminous Materials 141 


REFERENCES. 


_ 186 “ The Influence of Sunlight on Paints and Varnishes,” J. Soc. Chem. 
Ind., 1908, 27, 311. 187 “‘ The Effect of Exposure on Bitumens,” J. Ind. 
Eing. Chem., 1913, 5, 15. 188 Proc. Amer. Soc. Testing Materials, 1915, 15, 
275. 189 “*The Effects of Exposure on Tar Products,” J. Franklin Inst., 
463, Oct. 1916. 19 J. Ind. Hng. Chem., 1917, 9, 743. 192 J. Soc. Chem. 
Ind., 1909, 28, 694. 1% “The Light Sensitiveness of Petroleum Asphalt,” 
Chem. Zeit., 1915, 39, 832. 1% Trans. Faraday Soc., 1923, 19, 314. 


Bibliography. 

W. W. Wall, ‘‘ Process Year Book,”’ 26, 133. Eder, ‘‘ Geschichte der | 

Photographie,’ 1905, i, part I, p. 133. Nicolescu-Otin, Bull. Soc. Scv. 

Acad. Roumaine, 1920. Meigs, J. Ind. Hng. Chem., 1917, 9, 655. Rosinger, 

Kolloid-Ztg., 1914, 15, 177. Klimont, Oesterr. Chem. Ztg., 1914, 16, 309. 
Wilson, Highway Engineer and Constructor, 1920, June 27. 


CHAPTER XIX 
BITUMINOUS FABRICS 


Roofing Felt—Floorings and Floor Coverings—Bituminous Cements, Insulat- 
ing Coverings and Papers—Waterproofing and Damp Coursing—Manu- 
facture and Uses of Bituminous Fabrics. 


BiruminiseD fabrics are utilised in roofing, flooring, water- 
proofing, and for sheathing and insulating purposes, and they will 
be considered in detail under these headings. 

Sheet Roofings.—These are composed of a single layer or a plurality 
of layers together, each layer being composed of a woven or felted 
fabric, which is saturated and/or coated with suitable bituminous 
materials, the bituminous materials being chosen largely on their 
ability to withstand weathering.1® 

Both felted and woven fabrics are chosen, but the former are 
preferable, as they absorb a larger amount of bituminous material, 
and to a more unform degree than is found possible with the latter 
type of fabric. Roofing felt is composed of a variety of fibres, the 
following, together with their approximate relative durability, 
expressed numerically, being, according to Abraham : *° 


WOO]. sciscensenceneseyspedee gue da'nms gens kaa cuneate 100 
COUEOR nn. ie esclenaanegnassuntadunsecnsadanes sean een ne nanan 60 
Jute and manilla ...4..0s00.0. seseeeay seen tions 5h eee 0s nnn 44. 
Paper (including mechanical and chemical wood fibres). 20 


Wool fibres, besides being the most durable, are least affected by 
exposure to moisture and the sun’s rays: incidentally they are 
the most expensive. Numerous substitutes for felting have been 
suggested, such as leather, cane, straw, coconut, moss, peat, sea 
grass, and numerous patents relative thereto have been taken out, but 
in most cases the above substitute fibres result in increasing the 
brittleness or porosity of a felt with which they are incorporated. 
In regard to woven fabrics, the most usual are hessian (of jute 
fibres), and duck (of cotton fibres). 

The details of manufacture of the fabrics, and the technique of 
their saturation or coating with appropriate bituminous material, 
and the type of machinery employed are outside the scope of our 
survey. The materials generally to be recommended for the 
impregnating of the fibres and fabrics should be of soft consistency 
at ordinary temperature, with a penetration of more than 60 at 
25° C. (Test 9b), a consistometer hardness (Test 9c) of less than 15 at 
25° C., and a fusing point of 80—140° F. 

The following classes of bituminous materials have been recom- 
mended in this connection for saturation : 


Group I. Pure native asphalts, petroleum residual asphalts, 
142 


Bituminous Fabrics 143 


blown petroleum asphalts, and the pitches from wood tar, rosin, 
bone tar and fatty acids, either singly or blended to give the right 
consistency. If they are too hard they may be blended suitably 
with the softer grades of the pitches already enumerated, as well 
as with animal or vegetable fatty oils and wool grease. 

Group IJ. Oil-gas-tar pitch, water-gas-tar pitch, coal-tar pitch, 
coke-oven pitch, wood-tar pitch and rosin, bone-tar and fatty acid 
pitches, alone or in combination, or, if necessary to effect the desired 
consistency, with the corresponding liquid tar, previously evaporated 
to expel the highly volatile oils, etc. 

The tar and pitch compositions in Group IT (except the fatty acid 
pitch) are used mainly for manufacturing multiple-layered prepared 
_ roofings, and for single-layer tarred felt, which is to be used in built- 
up roofings of more than one course of fabric. Only Group I 
compositions are recommended for general use, on account of their 
greater weather-resisting characters. 

The characteristics of tar and pitch composition should corre- 
spond with those for a soft coal-tar pitch, 2.e., one having a fusing point 
120—160° F. (cube method). Saturating mixtures prepared from 
asphaltic products should comply with the following characteristics, 
according to particulars given by Abraham : 


(1) Viscosity at the saturating temperature should be as 
low as possible to accelerate the speed of absorption by the 
fabric. 

(2) Penetration at 25° C. should be in excess of 60, and con- 
sistency less than 15, to prevent brittleness in the fabric. 

(3) The susceptibility factor should be as low as possible, 
and preferably below 30. 

(4) The saturant should be ductile. 

(5) Fusing point 110—150° F., and as low a content of 
volatile matter as possible—less than 3% after 4 hours at 
500° F. 

(6) Preferably 97° or more of constituents soluble in carbon 
disulphide. 

(7) Should be weatherproof. 


The most commonly used materials for saturation purposes are 
soft coal-tar pitch, soft residual asphalt, and soft blown petroleum 
asphalt. A recent U. 8S. Government 1% specification for coal-tar 
pitch for roofing purposes requires that the pitch when freshly 
melted should be glossy black, and not dulled in one week ; m. p. 60— 
65-5° C., specific gravity 1-22—1-34, ductility—minimum 50 cm.; 


144. Blacks and Pitches ‘ 


free carbon content 15—30%. In the distillation test not more | 
than 12% by weight should distil over below 300° C., and the 
distillate should show a specific gravity not less than 1-03. 

Asphalt for use with asphalt saturated rag felt for roofing and 
water-proofing, and in the construction of mineral-surfaced roofing 
on an incline of not more than 3 in. to the foot, may be either 
petroleum residual asphalt or a mixture of refined Trinidad asphalt 
with petroleum asphalt, according to the latest U.S. Government 
specification,’®? which requires that the material when freshly 
melted shall be uniformly glossy and on ageing for one week its 
surface shall not become dull or show any separation of oil, grease, or 
wax. The asphalt shall further have : 


M. p. (ball and ring method) 60—73° C. 

Penetration 25—50 at 25° C., with a minimum of 10 at 0° C. 

Ductility at 25° C. to be 5 cm., preferably not less than 20. 

Soluble in carbon disulphide (in case of petroleum asphalt 
only) minimum 99%. 

Ash (in case of mixture containing Trinidad asphalt), mini- 
mum 20%. 

The ash must show the characteristics of that from Trinidad 
asphalt. | 


Naturally a great variety of modifications of the foregoing methods 
of using bituminous materials in the construction of roofing fabrics 
are to be found, and many might be enumerated. For instance, 
an impregnating material resembling rubber and suitable for coating 
millboards and textile fabrics has been patented by O. Schreiber.!*® 
Stearine pitch, wool pitch, or even coal-tar pitch or petroleum 
pitch is heated, cold air forced through, and during this treatment 
suitable oxidising materials are added. A somewhat similar material 
from the point of view of its applicability can be obtained by treating 
wool pitch with sulphur at temperatures up to 300° C.1% 

Floorings.—Bituminous materials find considerable use in the 
construction of floorings laid down in somewhat the manner of a 
concrete floor, over which they have the advantage of a certain 
resiliency. Both natural and artificial asphalts, with or without 
suitable fluxing, are used, and mineral aggregates in the nature of 
crushed limestone, finely-graded sand are added, and finely-powdered 
pigments and coloured metallic oxides, such as red oxide of iron, 
chromium oxide, etc., may be added to give a decorative effect .?°° 

This type of floor covering is laid down whilst of plastic trowelling 
consistency, the bituminous material being melted before admixture, 


/ 


Bituminous Fabrics 145 


and the matrix on cooling hardens to a smooth, hard surface which 
wears better than a concrete surface. 

As coverings for floors, but used in a somewhat different manner, 
there has grown up during the last fifteen years the manufacture of 
substitutes for linoleums and the like, bituminous materials, notably 
fatty acid pitches, being employed, the technique of which is 
somewhat analogous to that of linoleum manufacture (cf. ‘‘ The 
Chemistry of Drying Oils,’ by L. 8S. Morrell and H. R. Wood). 
The finished product is prepared in rolls and laid down in squares 
and strips. The use of stearine pitch in this connection was patented 
during the World War,?°! and very considerable quantities of medium 
soft stearine pitch found application in the manufacture of floor 
coverings, where its plasticity, high viscosity and ready hardening 

on exposure render it valuable. | 

Bituminous Cements.—These are of plastic consistency and can 
be utilised in the manner adopted for handling lime-mortar and 
cement, and their use is for joining, filling in and repairing of damp- 
proof masonry. They consist of : 


1, Bituminous base with or without the addition of vegetable 
_ oils, resins, etc. 
2. Mineral matter such as finely-ground limestone, barytes, 
- etc., as filler. 
3. Fibrous matter such as shoddy, asbestos, slagwool, 
cotton flocks, to bind together the bituminous base. 
4. Volatile solvents such as petroleum products, wood and 
tar distillates, in which the base will dissolve. 


The bituminous materials should be blended to give a fusing 
point (K. & 8.) of 135—175° F., a consistometer hardness (Test 
9b) of 5—25 at 25° C., a susceptibility factor (Test 9d) below 25, and 
almost complete solubility in the solvent used. Further, the 
bituminous base or bases are melted together in the usual type of 
varnish kettle over direct heat, cooled until the mass begins to thicken 
and then the solvent is added. Alternatively, the ingredients of the 
base may be acted upon by the solvent in a closed, steam-heated 
and mechanically agitated tank. After the incorporation of the 
base and solvent, the other ingredients are added until the requisite 
_ pasty consistency is achieved. 

Numerous acid-proof cements and acid-proof layers for floors 
are in use containing coal-tar pitch and other pitches in admixture 
with cement, fireclay, graphite, asbestos fibre, and other suitable 


materials.2°2 The cements are particularly useful in the making of 
10 


146 Blacks and Pitches 


joints in chemical plant, earthenware pipes, etc., and the bituminous 
material serves partly to bind together the various ingredients of 
the cement, and further, in virtue of its resistance to air and 
water, corrosive acids and chemicals generally, is invaluable in 
chemical and allied works, where steam and acid and other chemical 
fumes are encountered. 


Water-proofing and Damp-proofing. 

Their impermeability and resistance to the effects of moisture, 
make many bituminous materials and pitches invaluable in 
the prevention of the passage of moisture through porous 
constructional materials. By damp-proofing, according to G. J. 
Ward,?° is implied the prevention of the passage of water through 
brick, concrete or stone by capillary action; water-proofing or damp- 
coursing is the prevention of the passage of water under pressure 
through the walls of tunnels, conduits, tanks, etc., and calls for more 
than the comparatively thin layer of material which suffices to 
exclude moisture in damp-proofing work. 

According to Ward, a damp-proofing compound must have several 
characteristics to fit in for its work. It must, first of all, yield a 
film which will be impervious to water, and must be durable even 
under decided temperature changes. It must be capable of easy 
and rapid application, and must dry fairly rapidly, so that, if neces- 
sary, more than one coat may be applied without any great loss of 
time. It must bind well to the surface on which it is applied, and 
must be inexpensive. 

A great variety of damp-proofing compounds has been tried, but 
bituminous varnishes have generally proved so satisfactory in this 
respect that they are now consumed in very large quantities. 

A bituminous varnish, to function satisfactorily in damp-proofing 
work, must have certain definite properties.*°* In the first place, 
the varnish must be of a durable nature, maintaining its elasticity 
indefinitely. The percentage volatile at 100° C. is kept low as com- 
pared with the bituminous varnishes commonly applied to structural 
steel. This permits the attainment of a heavy consistency, which 
is desirable in order that in application a fairly thick coating is 
obtained. A thin coating applied to a porous surface, such as con- 
crete, is drawn for some distance into the pores of the material, and 
fails to make a seal unless a number of coats are applied. The 
varnish must set within 8 hours, but may remain somewhat 
tacky for a period of several weeks. Finally, it must possess ad- 
hesiveness, bonding well to the surface on which it is applied, and 


Bituminous Fabrics 147 


must be capable of acting as a foundation for plaster. The fact that 
these materials may be plastered on directly is one of the important 
considerations in their use. Experience shows, however, that the 
presence of certain materials or combinations enhances the effective- 
ness of the coating in its work. For instance, the presence of a 
percentage of stearine or fatty-acid pitch may be found to impart a 
desirable adhesiveness to the coating in addition to the great merit 
this material possesses of stability and retention, unimpaired, of its 
weathering and ageing properties after long exposure. 

The only satisfactory criterion of the value of a bituminous 
varnish for damp-proofing work is an actual test conducted in a 
manner which parallels actual practice as nearly as possible. Two 
coats should be applied to the clean, dry, slightly rough surface 
selected, allowing sufficient time for setting between coats. It is 
necessary to obtain perfect continuity of the coating, any bare or 
thin places rendering the results worthless. The final coat of damp- 
proofing varnish is left slightly rough, and a coat of plaster applied. 
This is subsequently painted with a light-tinted flat paint. A 
satisfactory damp-proofing varnish prevents any appearance of 
moisture on the plastered wall, even when the outside of the wall 
is subjected to the action of water for lengthy periods. 

Coal-tar pitch for use in this way, where the pitch is not exposed 
to a temperature in excess of 35° C., except during its installation, 
‘and where it is not subjected to vibration, should have the following 
characters : 2°4 Freshly-melted, the material must have a uniform 
black, glossy colour, and after ageing for one week must not become 
dull or show any separation of oily constituents. The freshly-fractured 
material must present a satin-black surface, m. p. (cube in water 
method) 52—60° C., free carbon 15—30%, d 1:22—1-34, minimum 
ductility 50 cm., and not more than 12% by weight, shall distil 
below 300° C., and the density of the distillate must not be below 
1-03. 

Natural asphalt is, of course, similarly used for water-proofing 
and damp-proofing, and a recent U.S. Government specification 29° 
requires asphalt for such use to be black and glossy when freshly 
melted; moreover, it must not become dulled in one week, it must 
have m. p. 60—77°C., penetration at 25°C. 25—50, at 0°C. a 
minimum of 10, and a maximum of 100 at 46°C. The ductility 
should be not less than a minimum of 15 cm. The maximum 
amount of volatile matter allowed is 1% at 63° C., whilst not less 
than 99% of the asphalt must be soluble in carbon disulphide. 


148 Blacks and Pitches 


Insulating and Sheathing Papers. 


Paper is specially treated to enable it to take a water-proofing 
material, either by coating, by saturation, or by both methods of 
application, and such suitably water-proofed papers find great 
application in the construction of cold-storage floors, insulated 
rooms and spaces on ships, refrigerator cars for the transport of 
perishable foodstuffs of all sorts, and in the lining of ice chests, the 
object being to prevent the transfer of heat into enclosures, which 
it is required should be kept cold, and conversely to prevent the 
egress of heat from enclosed spaces requiring to be kept warm.?°6 

Strong paper of open texture is the best to use in the manufacture 
of insulating papers, and generally the greater the number of layers 
used, the greater is the effectiveness of the insulated installation. 
In practice, the paper is introduced in the floors, walls and partitions 
of buildings between protective layers of wooden boards, one on 
each side of the cavity containing the chief insulating material, 
usually charcoal, cork or silicate cotton. 

For water-proofing the papers, petroleum residual pitches of 
asphaltic character and fatty-acid pitches find the most frequent 
use. M, Dupré and 8. Icard 7°’ have patented the use of stearine 
pitch for water-proofing paper and fabrics, either by direct applica- 
tion or after solution of the pitch in a volatile solvent, and such 
substances as tar or resin may be added to assist the formation of 
a coating material. These coatings are odourless, impermeable, 
very elastic, and when used in the form of pitch papers are excellent 
damp-proof coatings for the walls of cold-storage rooms. 

Cotton muslin strips 4—1 in. in width and 0-015—0-025 in. 
in thickness, passed through melted bituminous materials to fill 
up the pores of the fabric, form excellent coverings for electric 
cables, owing to the very high specific resistance of most bitumi- 
nous materials and pitches. Pure native asphalts, petroleum 
residuals, blown asphalts, fatty-acid pitches, either alone or with 
asphalts, are used, and they should be tacky and adhesive at room 
temperature, and should retain this property as long as possible on 
—exposure to the air. 

The desiderata for bituminous materials for such work are a 
consistency at 25° C. of less than 7, a susceptibility as low as possible, 
fusion temperature 27—40°C., and after being maintained at a 
temperature of 500° F. for 4 hours, the loss of volatile matter 
should not exceed 5%. 


Bituminous Fabrics 149 


Solid Impregnating Compounds. 


Such compounds with a bituminous material as a basis are 
prepared for field coils and stationary windings. The impregnation 
is completed in one operation, the coatings are more chemically 
inert, are better fillers and more resistant to moisture. The 
temperature of impregnation for a “‘compound”’ is higher than 
for an insulating varnish, but it should not be above 175° C., or the 
cotton covering may be carbonised. These impregnating com- 
pounds, unlike insulating varnishes, require no thinners and solidify 
on cooling, rendering the enclosed parts insensible to vibration. 

If an electrical machine be overloaded, the impregnating com- 
_ pounds will, unlike the varnishes, soften and may even melt; and if 

there be revolving parts, these may become exposed, owing to 
centrifugal force. Generally, the natural or petroleum residual 
asphalts and other materials used soften at 105—115° C., and do 
not become appreciably fluid below 150° C. The materials used— 
asphalt, stearine pitch, rosin and copal—are run together until 
water has been expelled, and, in order to make them resistant to 
mineral-oil, a certain amount of sulphur is incorporated. R. S. 
Morrell 2° quotes the following as being typical of impregnating 
compounds : 


1. 2. 3. 
100 parts neutral wool fat | 110 parts asphalt Stearine pitch heated 
200 «4, asphalt 200 ~=«, crude ozokerite to 220—285° C. 
50 =~«,, rosin 70  +«,, rosin 
so. « «=6Crosin oil 


(Andés) (Seeligman and Zieke, p. 426.) (Andés) 


Being durable and elastic, and not cracking or running when 
exposed to extremes of cold or heat respectively, the petroleum 
pitches (preferably those of asphaltic character), by reason of their 
high insulating properties, are valuable even alone in the manufacture 
of electric cable insulations. But, as F. Dupré *° has shown, only 
first-grade bituminous materials, whether natural or artificial, are 
suitable for cable masses, viz., those with the requisite elasticity, 
ductility and adhesiveness, and a fusing point of at least 75— 
95°C. If use be made of those with a fusing point of only 40—60° C., 
then the cable mass will lose its form when exposed to external 
temperatures exceeding 20—30° C. 


REFERENCES. 


195 “* Roofing Materials Committee Report,’ Bull. Amer. Railway Eng. 
Assoc., 1913, 14, 839. 19° U.S. Bureau of Standards, 1924, Circular 157. 
197 U.S. Bureau of Standards, 1924, Circular 159. 19° German Patent 


150 Blacks and Pitches 


208,378 of 1905. 419° German Patent 225,911. 9 English Patents 212,106 
and 212,188 of 1923. 1 English Patent 121,777 of 1917. 2 “‘ The 
Industrial Chemist,’”? May, 1925. 29% Oi and Colour Trades Journ., 1924, 
65, 1789. 2794 U.S. Bureau of Standards, 1924, Circular 155. 2795 U.S. 
Bureau of Standards, 1924, Circular 160. 2°% ‘‘ Modern Methods of Water- 
proofing,” by M. H. Lewis, New York, 1914. °°? French Patent 385,805 
of 1907. 298 ‘* Varnishes and their Components,” 1923, p. 305 (Oxford 
Univ. Press). 7° Chem. Zeit., 1918, 42, 445. 


Bibliography. 

Fleming and Johnson, ‘‘ Insulation and Designs of Electrical Windings,”’ 
1913. U.S. Bureau of Standards, 1924, Circular 162. S. E. Finley, English 
Patent 219,150 of 1923. ‘* Insulation and Insulating Materials,” Dictionary 
of Applied Physics, 3, 1922, Macmillan & Co. 


CHAPTER XX 
BITUMINOUS PAINTS, VARNISHES, ENAMELS AND JAPANS 


Nature of Bituminous Bases Used—Volatile Solvents to be Used—Bituminous 
Paints and Varnishes Protective against Rusting and Exposure to 
Chemical Agents—The Jellying of Asphalt Paints—Japans and their 
Uses—Pitting of Japans. 


oe 


PAINTS, varnishes, enamels, black japans, Brunswick blacks, stoving 
blacks are all prepared in the liquid state, and their consistency is 
regulated by the amount and nature of the solvent incorporated 
in the mixture. In this chapter attention will be confined to 
such of the above manufactured products as contain a bituminous 
base or material as an essential part of their composition, and, 
furthermore, they will be considered from the point of view of their 
composition, properties and uses. The technique of their manu- 
facture closely simulates that of the manufacture of paints, varnishes, 
etc., in general, and the reader is referred to any of the well-known 
volumes dealing with paint and varnish manufacture for details of 
plant and modus operandt. 

Bituminous Paints.—These consist of a bituminous base, a 
volatile solvent with or without the addition of vegetable drying 
oils, resins, fillers, pigments, etc., intended to dry or set by the 
spontaneous evaporation of the solvent, leaving a firm coat on the 
object painted. Generally those bituminous materials are chosen 
which will weather well on exposure to air, moisture and sunlight, 
and which are unattacked by mineral acids, caustic alkalies, cyanides 
and chemical fumes generally. One precaution that is necessary 
is to avoid the use of a bituminous base in any environment which 
will bring it into contact with the solvent action of any distillate 
(either in liquid or vapour form) derived from the same source as 
the bitumen itself, e.g., coal-tar pitch should not be used as a paint 
or coating for materials which come into intimate contact with a 
coal-tar distillate such as coal-tar naphtha. 

The bituminous paints may be divided into four groups con- 
taining : 

(1) Native asphalts, asphaltites, residual petroleum asphalts 
and all the pitches, with or without a filler, and suitable volatile 
solvents. 

(2) Bituminous substances, resinous substances (damar, 
sandarac, rosin), with or without a filler, or a coloured pigment, 
and suitable volatile solvents. 

(3) In addition to bituminous substances, animal or vegetable 


fats and oils such as linseed, tung, soya, fish, cotton, and perilla 
151 


152 Blacks and Pitches 


oils, raw or thickened, and in conjunction with driers, and 
suitable volatile solvents. 

(4) Bituminous substances, resins in combination with 
animal or vegetable fatty oils with or without mineral fillers 
and with or without pigments, and the addition of suitable 
volatile solvents. | 


The ‘‘ resins ’’ used may be common rosin, the damars, sandarac 
and Manilla, Kauri and Congo copals. These resins readily com- 
bine with the bituminous substances either by dissolving directly 
in the solvent or by first fluxing together. 

Vegetable and animal fats improve the weathering power of a 
bituminous paint and therefore should be added in the role of a 
flux. The harder the bituminous base and the higher its m. p. 
the larger is the amount (%) of the fatty oil that can be incorporated 
into the admixture. 

Fillers added must be of low specific gravity, finely powdered 
(they should pass through a 200-mesh sieve) and their function is 
to harden a paint and also to cheapen it. 

The solvents used in the preparation of bituminous paints 
comprise the following classes : Se, 

1. Petroleum Products—gasoline, naphtha (benzine), white spirit, 
and kerosene and their sub-fractions. (White spirit is midway 
between the low flash, boiling point and solvent power of gasoline 
on the one hand and the higher flash, boiling point and solvent 
power of the kerosene.) 

2. Coal-tar Distillates—in the order in which they distil benzols, 
toluols, xylols, solvent naphthas. 

3. Wood Solvents—acetone oils, light wood oil, heavy wood oil 
(creosote), wood turpentine, pine oil, rosin spirits and rosin oil. 

4, Manufactured Chemical Solvents—comprising carbon disul- 
phide, carbon tetrachloride and the non-inflammable chloro-com- 
pounds such as C,H,Cl,, etc. 

The comparative volatilities of some of the commercial solvents 
generally used in bituminous paint manufacture are for 2 c.c. of 
each solvent evaporated under identical conditions from a metal 
surface 34 in. square, according to Abraham, as follows: 


GS iii ahal saevsiesdertkn es ae 34 mins. Turpentine ,...0.s.0essees 142 mins. 
OSES Mi ON cpaithea nes aeaney cn § 4, ,, Wood turpentine ...... 480 ,, 
90% Dentol ne ceusesctses 134 ,, 80° gasoline ............... RES 
560% benzol. .Siehizr 23 e 66° benzine .............0. 16 see 
Commercial toluol ...... 33 3 Kerosene ...sséiesnschen Oe eee 475 5 


Solvent naphtha ......... 107 


Bituminous Paints, Varnishes, Hnamels and Japans 153 


The proportion of solvent used depends on (1) the nature of 
the bituminous base, (2) the solvent capacity of the particular 
solvent used, (3) the consistency required to be possessed by the 
finished paint. Generally it varies in amount from 20% to 80%, a 
smaller percentage being used in heavily-loaded paints for masonry, 
and for sealing joints in compound sheet roofing. 

Light-bodied paints containing a larger percentage of solvent 
are used when it is desired to secure great penetration, rapid drying 
properties or when the paint is for dipping purposes. 

In general, the higher the susceptibility of the base the lower 
will be the viscosity of the resultant paint. Petroleum residual 
asphalts and the pitches from wood tar, water-gas tar, oil-gas tar, 
and coal tar will form paints of lower viscosity than those fluxed 
with asphaltites, blown petroleum asphalts and the non-susceptible 
fatty-acid pitches. 

Tar pitches produced by the destructive distillagion of bones, 
wood, lignite and coal tar are more difficultly soluble than asphaltic 
materials and rosin and fatty-acid pitches. Tar pitches dissolve 
most readily in the following solvents, and in the order enumerated, 
carbon disulphide, coal-tar distillates, and resinous wood distillates. 
Of the other pitches, rosin pitch, fatty-acid pitches, bone-tar pitch 
and lignite pitch are the most soluble, whilst oil-gas—tar pitch, 
water—gas-tar pitch, wood- tar pitch and coal-tar pitch are the least 
soluble. | 

Dissolved in coal-tar naphtha, natural asphalts and such residual 
asphalts as those from Texas and Mexican Petroleum, produce 
excellent paints for the preservation of metal and outside iron and 
steelwork, and these paints will withstand dampness and all forms 
of chemical fumes and vapours. They are generally elastic and 
do not chip. . 

In a review of recent large-scale tests relative to the protection 
of metal surfaces, H. A. Gardner 24° mentions the wide use of 
bituminous coatings, which are often made by blending refined 
coal-tar pitch, asphalt, linseed oil, and oleo-resinous varnishes, 
subsequently thinning down with turpentine or light mineral thinner. 
When coal tar is used in the manufacture of paints, it should be 
refined. Ammonia and water in the tar are the active causes of 
non-adherence to metal. The presence of large quantities of free 
carbon or naphthalene in the tar will cause disintegration. For 
refining, the crude tar may be heated to approximately 115° C., 
holding it at that temperature until the water is evaporated. From 
5 to 10% of lime may be stirred in, in order to neutralise the 


154 Blacks and Pitches 


free acids. The tar may then be thinned with benzol or mineral 
spirits. If a rapid-drying paint is desired, a quantity of resinous 
varnish may be added. The addition of Chinese wood oil and 
asbestine in a coal-tar paint made along the above lines will aid 
in producing a film that is not so subject to “ alligatoring ’’ when 
exposed to the sun. However, none of these paints is as durable 
as a linseed-oil paint when exposed to the sun. Bituminous paints 
of the above composition are used as coatings upon pipe-lines in 
acid factories, tanks containing dilute acids, metal submerged in 
water, and for other similar work. For such purposes it is generally 
advisable first to coat the metal with a thoroughly hard-drying 
prime coating, made by adding + lb. of litharge to a gallon of pre- 
pared red lead or other rust-inhibitive paint. The bituminous 
paint may then be applied. Steel mine timbers subjected to sulphur 
water and gas, reservoir tanks containing water, submerged lock 
gates, tunnel metal, etc., may be efficiently preserved from corrosion 
by this method. 


Jellying of Asphalt Paints. 


In asphalt paints containing as part of the bituminous base 
fatty-acid pitch, bone-tar pitch, rosin pitch or any other pitch in 
which fatty acids or other similar acids are present, care is needed 
in the choice of a pigment in those cases where the addition of 
pigment is essential or desirable. Such pigments as chrome-green, 
chrome-yellow, zinc oxide, 2.e., those containing a metallic base, 
react with free fatty acids and rosin acids to form insoluble soaps 
and cause a certain amount of solidification known as “ gelatinisa- 
tion,” ‘‘ jellying”’ or “‘livering ”’ of the paints. In a recent con- 
tribution to the discussion of this subject F. Singleton 211 contends 
that the presence of water is an essential auxiliary factor in causing 
“ livering ”’ or thickening. 

Furthermore, a paint which jellies slowly in an unrefined solvent 
will jelly more rapidly in the same solvent after the latter has 
been subjected to acid and alkali refining. A thin paint on jellying 
will precipitate and remain as two layers. Thicker paints may 
settle out, but the incrustation of the layers so increases that in time 
the two layers may appear homogeneous. 

Recently the subject has received attention at the hands of H. C. — 
Fisher,212 who has found that sulphuric acid will cause asphalt 
paints to jelly, whether it is added to the base before dissolving, 
to the solvent before dissolving the base in it, or to the finished 
paint whether hot or cold. The rate of jellying appears to be 


-— 


Bituminous Paints, Varnishes, Enamels and Japans 155 


proportional to the amount of sulphuric acid present. Under 
certain conditions such substances as caustic soda (NaOH) or 
sodium sulphate will cause thickening of asphalt paints. In the 
case of steam blowing of asphalts to remove sulphur compounds, 
some of these latter may give rise to sulphur dioxide and ultimately 
to sulphuric acid. 

The rate of jellying of paints made from air-blown petroleum 
asphalts is dependent on the nature and composition of the bitu- 
minous ingredient and on the solvent used. <A petroleum residual 
asphalt blown with air in contact with lime (CaO) jellies extremely 
slowly, when contrasted with the same material not blown in contact 
with lime. 

Furthermore, bituminous bases that are hard and at the same 
time possess tough and rubber-like properties (7.e., low susceptibility 
factor, considerable elasticity, resilience and tenacity) when used 
alone are apt to gelatinise after solution in the volatile solvent. 
This is particularly the case with hard, rubbery, fatty-acid pitches, 
such as those from cotton black grease distillation and wurtzilite 
asphalt. The underlying causes in these cases are more obscure 
and uncertain than in the case of paints where there is: possibility 
of the formation of insoluble soaps. 

In an account of the use of bauxite as a refining agent for 
petroleum distillation by A. E. Dunstan, F. B. Thole and F. G. P. 
Remfry 213 mention is made of bauxite as a polymerising agent, 
polymerisation of unsaturated hydrocarbons largely present in 
cracked spirit taking place in contact with the bauxite resulting in 
the formation of gums of high molecular weight and boiling point. 
Two methods of refining such cracked spirit are available. In one 
of these the gumming polymers are washed out of the bauxite and 
in the subsequent distillation remain in the still, and a non-gumming 
distillate results. From the aspect of asphalt paints and their 
liability to jellying the importance of removing these polymers 
from bauxite-refined kerosene and white spirit is apparent. 

Black Japans.—The term “Japan” is intended to define the 
dark-coloured menstruum which is applied to the surface of metals, 
wood, or other fabric and subsequently hardened by baking. The 
japans are used mainly in high-class coach work, and the specific 
purpose of black japans is the production of a brownish-black ground 
of a particular translucence appearing as though their colour were 
reflected from an under surface; in this respect the japans differ 
from such pigmented preparations as black enamels, which appear 
to reflect colour from the surface only. 


156 Blacks and Pitches 


The base of cheap japans is solely a bituminous material, but 
the highest grades contain, in addition, a vegetable drying oil with 
or without the addition of some gum resin, and according to the 
nature of the ingredients and the method of treatment the japans 
may vary from an opaque black to a translucent brown—but all 
are extremely hard, tough and resistant to abrasion. 

The bituminous materials used are solid and semi-solid native 
asphalts, such as the purest forms of gilsonite, Barbados and 
Trinidad manjak, and in some cases residual asphalts from aromatic- 
base petroleums having the property of hardening on baking. 
Toughness may be imparted by fluxing with a small percentage 
of blown petroleum asphalt or fatty-acid pitch. Fatty-acid pitches, 
which have been overheated in the course of manufacture and have 
thus lost their more volatile constituents, and become partly poly- 
merised, are particularly useful in the preparation of black japans, 
even to the extent of being used without further admixture. 

Bituminous materials for use in the manufacture of japans 
must fulfil the following requirements : | 


1. They must be homogeneous and free from mineral matter, 
particularly any of a gritty nature. 

2. They should be opaque and have a black streak. 

3. They should possess a distinct conchoidal fracture and 
brilliant lustre, should not flow or lose their shape and should 
retain sharpness of angles even when immersed in boiling water. 

4, They must not separate, curdle or gelatinise on thinning 
with petroleum naphtha. 

5. They must bake in a reasonable time to a tough, per- 
manently glossy coating without shrivelling or “ crazing.” 


Gilsonite and such glance pitches as manjak will blend with fatty- 
acid pitch, and the resulting mixture can be thinned with petroleum 
naphtha to brushing consistency. But a tougher and more elastic — 
japan may be prepared by incorporating a proportion of thickened 
linseed oil, and incidentally the gloss is improved. Semi-drying oils, 
which will oxidise to tough coatings at elevated temperature, may be 
substituted for linseed oil, especially if boiled and combined with 
driers. z: 

_ Semi-glossy and flat black japans are prepared by grinding 
carbon black into the foregoing mixtures; the resulting baked 
surface then has an appearance resembling hard rubber. 

Japans are applied to surfaces by dipping, spraying, flowing or 


Bituminous Paints, Varnishes, Enamels and Japans 157 


brushing, and where only a thin coating is required probably a 
mechanically-operated spraying appliance yields a more uniform 
surface than results from brushing. The coated surface is then 
heated in special japanning or stoving ovens for 1—4 hours at a 
temperature of 95—220°C., depending on the composition of the 
japan and the nature of the material being coated. Generally 
wooden and similarly slightly porous articles require more baking 
than metals, and modern practice resorts more to higher temperatures 
for shorter periods of time than to the converse. 

As japans do not invariably possess a great degree of elasticity 
or weather resistance, the practice is resorted to of coating them 
with a suitable finishing varnish, as in coach japans, but generally 
it may be said that a baked japan forms a harder, tougher, and more 
weather-resistant coating than that of a bituminous varnish left 
to air-dry at room temperature. 

The art of the varnish-maker consists in the preparation of a 
japan of great depth and intensity of colour without employing so 
high a proportion of pitch or suitable bituminous material that 
solubility of the latter in the resultant coat takes place, a condition 
manifesting itself, as Morrell 2°8 indicates, by the appearance on the 
finished work of an undesirable greenish fluorescence—the “ green- 
ing ” of the japan. 

As Morrell 2° also points out, the shade is difficult to control : 
some japans yield a chestnut-black coloured film, due to the variety 
of pitch used. The latter should be as free as possible from volatile 
bodies likely to interfere with the lustre and to leave the film tacky. 
The coating should stand polishing the day following application. 
The following formule are quoted by Morrell?°8 as being very roughly 
representative : 


1. 2. 
RN PIT es kd unaxs Glyde ke sade cha dveSesadesphe es 25 20 
Natural or petroleum asphalt ............... 8-4 20 
DEUEMMIDS oe 4 5 hc ogre tenged cas save vers ss4cebesses 16-8 20 
PIMPLE Yada we sings ie vebcing poh 00 Wake vad seas’ 49-8 20 


_ Attempts have been made to introduce aniline blacks in place 
of pitches to produce a more intense black, but the addition appears 
only to impair the drying power of the film. 

Some japans consist of a bituminous base with boiled oil and a 
petroleum thinner, and thus approximate to the ordinary air-drying 
Brunswick-black type of varnish. 

A type of japan termed a Black Stoving Enamel is prepared by 
incorporating a considerable amount of drying oil with the solid 
bituminous base, and is used for insulating armatures and field coils 


158 Blacks and Pitches 


of motors and dynamos. The armatures or coils are thoroughly 
dried in a suitable oven to remove all traces of moisture, and then 
dipped whilst hot into the cold japan, and subsequently baked for 
8—12 hours, or even up to 24 hours, at about 85—95°C. The 
resulting hard-baked bituminous japan protects the cotton or other 
fibrous insulation wrapped round the coils from moisture and 
chemical fumes, and if properly prepared and baked will withstand 
currents of extremely high voltage. Such baking or stoving varnishes 
must not soften when applied to armatures, and to prevent brittle- 
ness, which would have a deleterious effect, it is advisable not to 
incorporate resin with the japan, owing to the pea: of resin to 
impart brittleness. 

In search of the best type of coating for iron vos used to 
hold acid plating solutions, Andés 214 found an enamel varnish 
somewhat similar to a japan by reason of composition and method 
of preparation the most suitable on account of its elasticity, its 
behaviour in the bending test and resistance to blows. This asphalt 
stove varnish was made from gilsonite, a thickened linseed oil 
(stand oil) and tar. After application to the metal surface, the 
varnishes were stoved at from 100 to 135° C., a second coat being 
subsequently applied and dried in the same manner. 

One of the defects to be countered in the preparation of baking 
japans is that of ‘‘ pitting,’ and a variety of causes may operate 
to bring about this objectionable feature. H. Gardner and P. 
Holdt,?1 in a review of the causes of this trouble, submit a number 
of important points as follow : 

Oils free from “‘ foots ”’ should be used; the bituminous materials 
selected must be free from mineral matter, and greasy, improperly 
ground carbon blacks, where pigments are required, should be 
avoided, whilst petroleum thinners of high boiling range and con- 
taining large amounts of non-volatile residues may be responsible 
for pitting and contraction of films. . 

Lack of cleanliness in the kettles and the containers for the 
japans—i.e., contamination by residues of polymerised oils and 
various forms of varnish—must be avoided. The thinners to be 
used should be added slowly, otherwise separation of some com- 
ponents of the japans may occur, which are difficult to redissolve. 

It is also recommended that surfaces to be japanned be free 
from grease and be chemically clean, in order to inhibit an unsatis- 
factory flow, and the japan should be applied warm to warm metal, 
the temperature in the japanning oven being raised gradually after 
the freshly-japanned articles have been placed therein. 


Bituminous Paints, Varnishes, Enamels and Japans 159 


The British Thomson Houston Co.?!6 claim that a black japan 
can be made with water thinners by incorporating 5 gallons of japan 
base (asphaltic base and a drying oil) with 10 gallons of water 
containing half a gallon of ammonia solution (s.g. 0-9) and 10—20% 
by volume of a 20% solution of glue. Another proposal of a similar 
character involves the preparation of an emulsion of an asphalt 
oil base in water and the deposition of this base on the metal by 
means of an electric potential difference maintained in the bath 
containing the emulsion; the object to be japanned is made the 
anode, and if large should be pre-heated before immersion in the bath. 
Since the japan is deposited free from solvent, there is no resultant 
drip on conveying the japanned object to the baking oven.??’ 

More recently details are to hand of another method of making 
a japan in water solution.?!§ 


Avw-drying Black Enamels. 


These are made in a manner analogous to that adopted for 
black japans, but materials of less carefully selected quality are 
chosen. Some contain only a pitch, boiled oil, and turpentine, and 
are of the Brunswick-black type, for which Morrell? quotes the 
following representative formule : 


(a) 45 lbs. of pitch, 6 gallons of boiled oil, and 6 lbs. of litharge, 
boiled until stringy and then cooled and thinned with 25 gallons 
of turpentine. 

(b) 32 lbs. of gilsonite, 14 gallons of boiled oil, and 54 gallons 
of turpentine. 


A quick air-drying black varnish for all sorts of iron work can 
be made by melting 28 lbs. of coal-tar pitch with 28 lbs. of a 
petroleum asphalt, and boiling for 8 hours, with subsequent addition 
of 8 gallons of boiled oil, which is incorporated by heat. After 
adding 10 lbs. of litharge and 10 lbs. of red lead, the mixture is 
boiled until the mass will set hard between the fingers. On cooling, 
the mixture is thinned with 20 gallons of turpentine. The varnish 
will dry in 1—2 hours. According to Morrell,2°® the addition of 
small quantities of coal-tar spirit (cresylic acid) improves the solu- 
bility of the components of these black varnishes, but diminishes their 
drying power, and therefore is restricted to stoving black enamels. 

Some idea of the requirements to be fulfilled by air-drying 
black enamels may be gathered from following British specifications 
extracted by permission of the British Engineering Standards 
Association from their Reports Nos. 2X. 9, and 2 X. 10, respec- 


160 Blacks and Pitches 


tively, of Dec. 1920, official copies of which can be obtained from the 
Secretary of the Association, 28 Victoria Street, Westminster 
S.W.1, price 2d. each, post free. 


BRITISH ENGINEERING STANDARDS ASSOCIATION 
British Standard Specification for Aircraft Material. 


UnDERCOATING BirumiINous Paint. (2 X. 9, 1920.) 


1. Description.—The paint shall consist of a solution of high 
grade bitumen, and in addition to satisfying the clauses of this Speci- 
fication, shall comply with the special requirements of Appendix II. 

2. Consistency.—The paint shall be of such a consistency as will 
allow of easy application by brush or spray. 

3. Rate of Drying—The paint, when applied to a hard wood, 
shall dry at 70° F. (21° C.) in not more than 6 hours, to a glossy, 
smooth, hard surface, which does not become soft or tacky when 
the temperature is raised to 100° F. (38° C.). 

4. Klasticity—The film of the paint shall be tested for elasticity 
in accordance with Appendix I. 


APPENDIX I. 


Test for Elasticity. 


The paint shall be applied to a panel of 30 S.W.G. tinned iron 
and allowed to dry in a nearly vertical position for 24 hours at 70° F. 
(21° C.). The panel shall be bent rapidly double over a } in. dia- 
meter rod and straightened out again. The paint film shall show 
no sign of cracking at the point of bending. 


Apprnprix II. 


Special Test for Bituminous Paint. 


Two coats of the paint shall be applied to a wood panel, and 
after remaining 16 hours in bright daylight, a coat of Wood Oil 
paint (B.S. Specification X. 16) shall be applied. The film of paint 
shall become dry after not more than 8 hours, and shall adhere to 
the bituminous undercoating. 


BRITISH ENGINEERING STANDARDS ASSOCIATION 
British Standard Specification for Aircraft Material. i 


Arr Dryina Buack Enamet. (2 X. 10, 1920.) 


(NoTtE.—This material is to be used only for touching up Metal 
parts.) 


1. Description—The enamel shall be suitable for direct applica- 
tion by brush or spray. A single coat shall produce a complete 
covering. 


Bituminous Paints, Varnishes, Enamels and Japans 161 


2. Rate of Drying.—The enamel when applied to a metal surface 
‘shall dry at 70° F. (21° C.) in not more than 8 hours to a smooth 
glossy film. 

3. Hlasticity and Adhesion.—The film of the enamel shall be 
tested for elasticity and adhesion in accordance with Appendix I. 


APPENDIX I. 
Test for Elasticity and Adhesion. 


The enamel shall be applied to a panel of 30 S.W.G. tinned iron 
and allowed to dry in a nearly vertical position for 48 hours at 
70° F. (21°C.). The panel shall be bent rapidly double over a 
4 in. diameter rod and straightened out again. The enamel film 
shall show no signs of cracking at the point of bending and shall 
adhere to the metal surface. 


_A United States specification 2!9 for a similar asphalt varnish 
is more detailed : 

The varnish shall be composed of a high grade of asphalt, fluxed 
and blended with properly treated drying oils and thinned to the 
proper consistency with a volatile solvent. It must be resistant 
to air, light, lubricating oil, water and mineral acids of the concen- 
tration hereinafter specified, and must meet the following require- 
ments : 


Appearance.—Smooth and homogeneous; no livering or 
stringiness. 

Colour.—Jet black. 

Flash Point (closed cup).—Not below 30° C. (86° F.). 

Action with Linseed O1l.— Varnish must mix freely to a homo- 
geneous mixture with an equal volume of raw linseed oil. 

Insoluble in Carbon Disulphide—Not more than 1%. 

Non-volatile Matier.—Not less than 40% by weight. 

Fatty Matter.—Not less than 20% of the non-volatile. Must 
be liquid and not show any rosin by the Liebermann—Storch 
test. 

Set to Touch.—Within 5 hours. 

Dry Hard and Tough.—Within 24 hours. 

Toughness.—Film on metal must withstand rapid bending 
over a rod 3 mm. ( in.) in diameter. 

Working Properties—Varnish must have good brushing, 
flowing, covering and levelling properties. 

Resistance to Water.—Dried film must withstand cold water 


for 18 hours. 
11 


162 Blacks and Pitches 


Resistance to Oil.—Dried film must withstand lubricating oil 
for 6 hours. 

Resistance to Mineral Acid.—Dried film must withstand 
action of the following acids for 6 hours: sulphuric acid, 
s.g. 1:3 (about 40% H,SO,); nitric acid, s.g. 1-22 (about 35% 
HNO); hydrochloric acid, s.g. 1-09 (about 18% HCl). 


The original specification must be consulted for details as to 
the carrying out of these tests. Evidently the specification corre- 
sponds to that of an air-drying black enamel. 

Various air-drying black enamels and varnishes are in use, 
their composition being suited somewhat to their uses and require- 
ments. Such materials as Mexphalte, Patagonian asphaltum, 
Syrian asphaltum, etc., can be used without the addition of oils 
or driers. The asphaltum is melted slightly, then thinned down 
with 1—14 times its weight of white petroleum spirit, turpentine 
or even coal-tar naphtha to brushing consistency. The resulting 
enamel dries in about an hour to a fine varnish-like gloss, which. 
it retains. These enamels form excellent coatings for all classes 
of outside iron and steelwork, for fire grates and fenders, iron pipes, 

te., being not only water-proof and rust-preventing, but non-con- 

ducting and insulating. The rapidity with which these black 
varnishes dry depends mainly on the volatility of the thinner used 
in their manufacture. 


Insulating Varnishes. 


Owing to their high dielectric constants, pitches are valuable 
insulating materials, and a solution of the pitch with gum or resin 
in a suitable thinner is allowed to impregnate the insulating 
material—paper, silk, cotton, etc.—and after volatilisation of the 
solvent, a film of non-conducting and moisture-resisting material 
is left. The varnish should have great penetrating power, and 
the dried film should be sufficiently elastic to withstand the strain 
due to bending and to temperature changes. 

The functions of insulating varnishes are summarised by 
Morrell 2°8 as follows : 


1. To provide a waterproof coating with sufficient elasticity 
to withstand the movement between parts produced either by 
rotation or by magnetic or electric forces. 

2. To increase the insulating properties of the impregnated 
material. 

3. To protect the parts from the action of oils and acids. 


Bituminous Painis, Varnishes, Enamels and Japans 163 


4. To prevent excessive rise in temperature through their 
relatively high thermal conductivity. 


Insulating materials for treating paper and fabrics, and solid 
impregnating compounds have been dealt with in the previous 
chapter. Morrell 2°§ quotes the following as typical of oil and 
pitch insulating varnishes for impregnating windings : 


Stoving Black Insulating Varnish. 


300 parts of thickened linseed oil 
100 ,,  ,, petroleum residual pitch 
7. (i045), Suiphor 
ie ee »» litharge 
1 part of manganese dioxide 
100 parts of turpentine 
400 ,,  ,, light petroleum spirit 


The conditions governing chemical action in high-voltage wind- 
ings are given by Fleming and Johnson,?*° who state that chemical 
action occurs only where air pockets are present due to imper- 
fections in the windings, and then only when the voltage across 
them is high enough to produce a discharge. Oxidation then 
occurs in the air gap discharge, the effect on oils and gums being 
to produce organic acids, but asphalts and pitches are attacked only 
slightly, and paraffin wax not at all. The organic acids produced 
act in a strongly disintegrating manner on the varnish material. 

In a review of the chemical problems arising in connection with 
insulating varnishes, H. C. P. Weber #2! mentions that varnishes 
give rise to acidic oxidation products (cf. volatile fatty acids) of 
low resistance, though this behaviour is not marked in the case of 
asphaltic varnishes. For impregnating, the penetration depends 
on the viscosity, body, and colloidal nature of the varnish—for 
binding, the strength and rigidity are important factors. 


REFERENCES. 


210 Paint Manufacturers’ Assoc. of U.S., Circular No. 202, 1924, pp. 302- 
327. 211 ** Enamels,’ Chemistry and Industry, 1925, p. 25. 712 J. Ind. 
Eng. Chem., 1924, 16, 509. 213 J. Soc. Chem. Ind., 1924, 48, 1797. 214 Farb. 
Zeitung, 1923, 1260. 215 Circular 145, Educational Bureau Scientific Section 
Paint Manufacturers’ Assoc. of U. S. .. Feb., 1922. 216 British Thomson 
Houston Co., English Patent 155,427 of 1919. 217 Chem. Trades Journ., 
1920, May 15th. #18 W. P. Davey and General Electric Co., U.S. Patent 
1,472,716 of 1923. 219 Circular No. 104, Bureau of Standards, U. S.A., 1920. 
220 Fleming and Johnson, Journ. Inst. Elect. Eng., 47, No. 209. 221 Ind, 
Hing. Chem., 1925, 17, 11. 


Bibliography. 
S. H. Gilson, U.S. Patents 361,759, 362,076 and 415,864. R. 8S. Morrell 


and A. de Waele, ‘‘ Rubber, Resins, Paints and Varnishes,’’ 1921. A. R. 
Matthis, ‘‘ Les Vernis Isolants en Electrotechnique,”’ 1921. 
11* 


CHAPTER XXI 
BITUMINOUS PAVING MATERIALS 


Roadway and Pavement Construction—Surface Phenomena in connection 
with Asphalt Pavement Construction—The British Standard Specification 
for Tar and Pitch for Road Purposes. 


As we have already noted in Chapter IX, the first asphalt block pave- 
ment of which any record is now extant was laid down by Nabo- 
polassar (625—604 B.c.), the father of Nebuchadnezzar, but apparently 
the art was lost to mankind, for it was not until 1836 that asphalt 
was first used in London for foot pavements and in the United 
States in 1838, Seyssel asphalt from the Rhone Valley in France 
being the material employed. Later on we find asphalt roadways 
being constructed and Trinidad asphalt the material selected. 

At the present day bituminous materials for constructing pave- 
ments, coating the surface of macadam, or for use merely as a means 
of dust-laying are finding increasing world-wide use, and all or any 
of the following materials, either singly or in combination, may be 
used, according to circumstances : native asphalts, residual asphalts, 
blown petroleum asphalts, asphaltites and the various tars and 
pitches, such as those derived from gas- and coke-oven works. 
Native asphalts are, however, the most used, and in 1921 the esti- 
mated annual consumption (world’s) for paving was 669,000 tons. 

It is not possible to dwell here on more than one or two interest- 
ing aspects of a study which rightly belongs to the domain of High- 
way and Pavement Engineering and Construction. It has been 
suggested, however, in certain quarters that asphalt is unsuitable 
for roadway construction on account of its tendency to yield a 
slippery surface. As the causes which produce this effect are known, 
their elimination is possible by suitable technical control, and it 
is worthy of note that out of 140 miles of arterial roads around 
London only some 20 miles are made with a concrete surface—the 
rest have an asphalt surface. At the present day, an elastic or 
resilient surface is considered as the ultimate solution of the road 
problem, this being the only surface capable of withstanding the 
pounding action of modern traffic with its heavy loads and high 
speeds.2#2, In this respect, bitumen, according to its advocates, 
stands unchallenged—it offers great resistance to the effects of 
dampness and retains its smoothness of surface for many years. 

Undoubtedly, the peculiar properties of Trinidad asphalt are 
due to the colloidal suspension of clay present. This is not deposited 
from solutions of the bitumen, even after standing for years. It is 


owing to the presence of this colloidal clay, together with sulphur 
164 


Bituminous Paving Materials 165 


derivatives in the Trinidad asphalt, and to the sulphur derivatives 
in Bermudez asphalt, that these materials are so desirable in road- 
way construction, for asphalt serves the purpose of cementing 
together the mineral aggregates and sands used in laying the different 
types of pavements and road surfaces. It is worthy of note that 
the Thames Embankment is a type of Trinidad sheet asphalt pave- 
ment laid on old macadam and Trinidad asphalt concrete. 

The surface of an asphalt pavement being an agglomeration of 
sand graded in size with a fine mineral dust and a bitumen in the 
form of asphalt of approved consistency, C. Richardson *?° regards 
the asphalt pavement as a heterogeneous system of two components, 
one a solid (the mineral aggregate) and the other a liquid (the 
bitumen). 

The importance of surface phenomena and the relationship of 
solids in colloidal suspension to the liquids with which they are 
associated is definitely recognised in this connection, and has led to 
investigations on the properties of mixtures of colloidal clay and 
petroleum residual pitches with a view to their use in pavement 
construction. This aspect of the subject opens up a very fruitful 
field for investigation. 

Already much work has been done in this direction in the manu- 
facture of bituminous emulsions, and amongst the materials which 
have been used to form emulsions of the dust-laying oils and the 
more solid and semi-solid bitumens may be mentioned: soaps, those 
consisting largely of ammonium oleate being the most favoured; the 
alkalies, when used with tars and pitches, containing phenolic 
bodies; colloidal clays and mineral matters; small amounts of 
colloidal vegetable substances such as the saponins and vegetable 
mucilages. 

In the typical sheet asphalt roadway we have the following to 
consider in brief outline : 


1. The Foundation or Base Course. 

This may consist of a brick or block roadway and some- 
times even of old macadam, but the most satisfactory foundation 
is probably 4 to 9 ins. thick of Portland cement concrete. 

2. The Intermediate or Binder Course. 

This may be either graded or ungraded coarse-aggregate 
bituminous concrete; broken stone is used, and this may be 
limestone or granite, and asphaltic sine 

3. Surface or Wearing Course. 

This is composed of graded sand and an asphaltic cement. 


166 Blacks and Pitches 


Typical asphaltic cements prepared from Trinidad and Bermudez 
asphalts respectively test as follows : 





From From 
Trinidad Bermudez 
asphalt. asphalt. 


(Test 7) Specific gravity at 77°F. ...........08.- 1-26 1:07 
(Test 9b) Penetration at 77° BF. wo... .cccescseeeeeees 65 65 
(Teast 9c) Consistency at 27°22. o.ssncineantnenponnts 7:9 8-0 
(Tést 100) Ductility at 777 oy. cra ccceesenese 21:5 17 
(Test 15c) Fusing point (cube method) ............ 148° F. 150° F. 
(Test 16a) Volatile matter at 325° F. in 5 hrs. ...... 2:°5% 32% . 
(Test 19): “Pixon Carbon o..scccss-seascredccecs uececee 6-1% 9-8% 
(Test 21a) Soluble in carbon disulphide ............ 65:7% 97-6% 
(Test 21c) Mineral matter ...,.......ccccccssescocsceees 29'5% 0:3% 


From a chemical point of view we have already (Chapter XII) 
seen that all the more or less solid bitumens consist of “‘ asphaltenes ”’ 
which impart cohesiveness and supply body and stability, whilst 
the “ petrolenes ”’ are extremely sticky and of cement-like nature. 
A solid asphalt cement should contain not less than 15% of 
‘‘ asphaltenes ”’ and not less than 70% of “ petrolenes ” to have the 
proper degree of stability and adhesiveness; the “ petrolene ’”? must 
be sufficiently sticky, otherwise the asphalt may not be suited as a 
cement. | 

H. Tindale 1° considers that the ‘‘ asphaltenes ” in road tars are 
their most desirable constituents, and if this contention be correct, 
it supplies additional confirmation of the fact that prepared hori- 
zontal retort tars are much more useful as road tars than those 
prepared from vertical retort tars, for the reasons already indicated 
by Wright,}°* viz., horizontal retort tars are less paraffinoid. 

The requirements of British Standard Specifications of Tars, Pitches, 
Bitumens and Asphalts when used for road purposes may be gathered from 
the following, extracted by permission of the British Engineering Standards 
Association from their Report No. 76, 1916, official copies of which can be 


obtained from the Secretary of the Association, 28, Victoria Street, West- 
minster, §.W. 1, price ls. 2d. each, post free. 


BRITISH ENGINEERING STANDARDS. ASSOCIATION. 


British STANDARD NOMENCLATURE OF 
TARS, PITCHES, BITUMENS AND ASPHALTS 
WHEN USED FOR ROAD PURPOSES. 


_ IntrRopuctTorRY REMARKS. 


The materials now used by Road Engineers for binding together the 
stones and other mineral aggregate used to form road crusts and road surfaces 
may be conveniently divided into three groups. These are :— 


Bituminous Paving Materials 167 


1. The tars and pitches obtained by the destructive distillation of 
coal or similar substances. 

2. The bitumens and asphalts which are found in nature, or are 
obtained artificially from asphaltic oils. 

3. Chemical binders, including the Portland and natural cements 
which owe their cementing value as road binders to chemical action, and 
which are not dealt with in the present report. 


Hitherto the term ‘“‘ bituminous material’ has been loosely applied to 
tar products as well as to bitumens and asphalts, but the Committee have 
from the first considered that it was desirable from the Road Engineers’ 
point of view to maintain a sharp line of demarcation between the two groups. 
The views put forward in correspondence from America and by American 
engineers of standing and experience have been carefully considered, but the 
Committee still adhere strongly to the view that the description ‘‘ bituminous ”’ 
should be applied only to the second group. 

In this country the first group of road binders, the coal tars and pitches, 
have been in use for many years, and as the Road Board in 1911 issued 
Specifications for the tars, tar oils and pitches, which they recommended 
for road purposes, these materials have already to some extent been defined 
by those Specifications. The Road Board early in 1914 issued a second 
edition of these Specifications. Only two classes of tar, and one class of 
pitch are dealt with, and as these Specifications are of such recent date, the 
Committee recommend that they be adopted provisionally as the British 
Standard Specifications for Tars and Pitches used for Road Work. 

The Committee find that the choice of names for the second group of road 
binders is a matter of some difficulty. This difficulty is increased by the 
fact that whilst it is desirable to obtain the concurrence of the American 
Engineers to the nomenclature and definitions which the Committee now 
propose, the adoption of the American nomenclature for the various materials 
composing this group would be liable to lead to confusion and misunder- 
standing in this country. 

The Committee have been very anxious to secure uniformity with American 
practice, and have carefully and fully considered the definitions adopted by 
the American Society for Testing Materials and by the Committee of the 
American Society of Civil Engineers, put forward by the American corre- 
sponding members, but it is felt that the definitions now decided on are 
preferable from the Road Engineers’ point of view, as they are based on those 
characteristics of the materials which can be most readily verified when 
employed for road making. 

In accordance with this view, the Committee consider that it is desirable 
to make a sharp distinction between coal-tar and paraffin-oil derivatives on 
the one side, and native bituminous substances and asphaltic oil residues 
on the other, and they are therefore unable to accept the American definition 
of Bitumen which would include the coal tars. 


DEFINITIONS. 
First GROUP. 
TAR PRODUCTS (PRINCIPALLY COAL TAR AND PITCH). 


Definition of Tar. 
1. Tar is the matter (freed from water) condensed from the volatile 
products of the destructive distillation of hydro-carbon matter, whether 
this be contained in coal, wood, peat, oil, etc. 


Prefix denoting source of origin or method of production. 
2. A prefix such as ‘‘ Coal,”’ ‘‘ Wood,” “* Peat,’ “‘ Gas Works,” “ Blast 
Furnace,” “‘ Coke Oven,”’ etc., must be added to the word ‘‘ Tar ’’ to indicate 
the source of origin or method of production. 


168 Blacks and Pitches 


Definition of Pitch. 
3. Pitch is the solid or semi-solid residue from the partial evaporation 
of tar. 


SECOND GROUP. 


BITUMENS AND ASPHALTS. 


Definition of Bitumen. 

4. Bitumen is a generic term for a group of hydro-carbon products soluble 
in carbon disulphide, which either occur in nature or are obtained by the 
evaporation of asphaltic oils. The term shall not include residues from 
paraffin oils or coal-tar products. 

Nore.—Commercial materials may be described as BrTuMEN if they 
contain not less than 98 per cent. of pure Bitumen as defined above. 


Definition of Native Bitumen. 
5. Native Bitumen is bitumen found in nature, carrying in suspension 
@ variable proportion of mineral matter. 
The term “‘ Native Bitumen” shall not be applied to the residuals from 
the distillation of asphaltic oils. 


Definition of Asphalt. 

6. Asphalt is a road material consisting of a mixture of bitumen and 
finely graded mineral matter. The mineral matter may range from an 
impalpable powder up to material of such a size as will pass through a sieve 
having square holes of } inch side. 


Definition of Native or Rock Asphalt. 


7. Native or Rock Asphalt is a rock which has been impregnated by 
nature with bitumen. 


Prefixes denoting Source of Origin. 


8. The Committee recommend that for convenience of identification 
prefixes denoting geographically the source of origin should be attached to 
each of the four terms defined above. 


BRITISH STANDARD SPECIFICATION FOR 
PITCH FOR ROAD PURPOSES. 


(Based upon the Road Board Specification No. 6 and published with the approval 
of the Road Board.) , 


Standard Pitch for Road Purposes in the United Kingdom shall be 
specified as under :— 


BRITISH STANDARD SPECIFICATION FOR PIrcH. 


General. 


1. This pitch is suitable for pitch-grouting. See ‘‘ Road Board General 
Directions for Pitch-Grouting.”’ 


a 


Consistency. 


2. The pitch is obtained of the required consistency most conveniently 
by running it off from tar stills in which the distillation of the tar has been 
stopped at the point at which the residual pitch will give a penetration of 
70 (or such other penetration as may be specified to suit climatic or local 
conditions) when tested at 25° Centigrade (77° Fahrenheit) on a penetro- 
meter. Harder pitch may be softened or cut back, in the still or in a mixer 
at the tar works, to the extent necessary for it to give this penetration, by 
the addition of tar oil of the grade specified below in Clauses 7 to 10. 


Bituminous Paving Materials 169 


Where pitch of the required consistency is not thus directly procurable, 
it may be prepared by softening commercial soft pitch, as specified below 
in Clauses 4 to 6, by the addition of tar oil as specified below in Clauses 7 to 
10. In preparing the softened pitch in this manner the tar oil is added to 
the pitch in the manner described under ‘“‘ Instructions for Melting the Pitch ”’ 
in the ‘‘ Road Board General Directions for Surfacing with Pitch-Grouted 
Macadam,”’ in such proportions that the resultant softened pitch will give a 
penetration of 70 (or such other penetration as may be specified to suit 
climatic or local conditions) when tested at 25° Centigrade (77° Fahrenheit) 
on a > penser with a No. 2 needle weighted to 100 grammes for five 
seconds. 


PREPARED PircH FROM TAR DISTILLERIES. 
General Characteristics. 


3. Pitch which has been procured of the required consistency directly 
from a tar distillery needs only to be thoroughly melted in the pitch heaters 
or boilers, but as a precaution against burning, | to 2 per cent. of tar oil may 
advantageously be put into the boilers with the pitch. 

Pitch which has been procured of the required consistency directly from 
a tar distillery shall not yield more than 4 per cent. of distillate below 270° 
Centigrade, or 518° Fahrenheit, on distillation as described below in Clause 5, 
and shall contain not less than 16 per cent. and not more than 28 per cent. 
of ‘‘ free carbon,’’ as defined below in Clause 6. 


COMMERCIAL Sort PITcH. 


Source of Pitch. 


4. The pitch shall be derived wholly from tar produced in the carboniza- 
tion of coal, except that it may contain not more than 25 per cent. of-pitch 
derived from tar produced in the manufacture of carburetted water gas. 


Fractionation. 


5. On distillation in a litre fractionating flask (a distillation flask without 
special fractionating column) one-half to two-thirds filled, the pitch shall 
yield the proportions by weight of distillates stated below; the temperatures 
of distillation being read on a thermometer of which the bulb is opposite 
the side tube of the flask :— 


Below 270° Centigrade or 518° Fahrenheit, not more than 1 per cent. 
of distillate. 

Between 270° and 315° Centigrade or 518° and 599° Fahrenheit, 
not less than 2 per cent. and not more than 5 per cent. of distillate. 


Free Carbon. 


6. The pitch shall contain not less than 18 per cent. and not more than 
31 per cent. by weight of free carbon. The free carbon is to be determined 
by the weight of the residue after complete extraction of all matter soluble 
in benzol or disulphide of carbon. The extraction is best carried out in a 
Soxhlet or similar apparatus by disulphide of carbon followed by benzol. 


TaR OIL. 
Source of Tar Oil. 


7. Tar oil to be used is preferably a filtered green or anthracene oil, and 
shall be derived wholly from tar produced in the carbonization of coal or 
from such tar mixed with not more than 25 per cent. of its volume of tar 
produced in the manufacture of carburetted water gas. 


Specific Gravity. 
8. The specific gravity of the tar oil at 20° Centigrade (68° Fahrenheit) 
shall lie between 1-065 and 1-085. 


170 Blacks and Pitches 


Freedom from Naphthalene and Anthracene. 


9. The tar oil after standing for half an hour at 20° Centigrade (68° Fah- 
renheit) shall remain clear and free from solid matter (naphthalene, anthracene, 
etc.). 

Fractionation. 


10. The tar oil shall be commercially free from light oils and water. On 
distillation in a litre fractionating flask (a distillation flask without special 
fractionating column) one-half to two-thirds filled, the tar oil shall yield the 
proportions by weight of distillates stated below; the temperatures of dis- 
tillation being read on a thermometer of which the bulb is opposite the side 
tube of the flask :— , 


Below 170° Centigrade or 338° Fahrenheit, not more than 1 per cent. 
of distillate (light oils and water, if any). 

Below 270° Centigrade or 518° Fahrenheit, not more than 30 per cent. 
of distillate (middle oils, and light oils and water, if any). 

Below 330° Centigrade or 626° Fahrenheit, not less than 95 per cent. 
of distillate (heavy oils, middle oils, and light oils and water, if any). 


REFERENCES. 


222 Sir Courtauld Thomson, reported in The Chemical Age, April 4th, 
1925, p. 329. 2% “*The Colloidal State of Matter in its Relation to the 
Asphalt Paving Industry,” 1917. 


Bibliography. 


‘* Manufacture of Bituminous Road-dressing Materials,’ J. A. Vielle, 
Eng. Patent 196,950 of 1921. C. J. Cruijff, Eng. Patent 201,813 of 1922. 
J. F. Wake and D. D. Spence, Eng. Patent 208,879 of 1922. FF. Morton, 
Eng. Patent 194,448 of 1922. Highway Engineer’s Year Book, 1924, Sir 
Isaac Pitman & Sons. ‘Streets, Roads and Pavements,’ by H. G. Whyatt, 
Sir Isaac Pitman & Sons. ‘‘ General Directions and Specifications relating 
to the Tar-Treatment of Roads,’ H.M. Stationery Office. 


APPENDIX I 


THE following is reproduced by the courtesy of the Director of 
the U.S. Geological Survey, Department of the Interior, Washington, 
the information contained therein having only recently been made 
available. 


CARBON BLACK 
PRODUCED: FROM NATURAL ee 
IN 1923 


By G. B. RICHARDSON 


Mineral Resources of the United States, 1923—Part II 
(Pages 89-90) 
Published September 29, 1924 


The production of carbon black from natural gas in the United 
States in 1923 amounted to 138,262,648 lbs., an increase of 104% 
over the production in 1922. The increase resulted from the 
expansion of the industry that followed the greater demand in 
1922 for carbon black by rubber companies. The number of pro- 
ducers of carbon black reporting to the Survey increased from 26 
in 1922 to 47 in 1923, and the number of plants operated from 43 to 
69. The operations resulted in over-production during the later 
part of 1923, as indicated by the quantity of stocks held in the 
hands of producers. Stocks increased from 2,434,547 lbs. on 
January 1, 1923, to 38,320,814 Ibs. on December 31. 

The production by States in 1923 as compared with that in 1922 
is shown in the following table. Louisiana led all the States in 
the quantity of carbon black produced, as it has in the last three 
years, and its output of more than 101,000,000 lbs. shows an increase 
of 142% over its output in 1922. The production of Kentucky 
in 1923 increased 134%. The production of West Virginia, on the | 
other hand, declined slightly. Texas joined the States producing 
carbon black in 1923. The production of Wyoming, Oklahoma, 
Montana, and Pennsylvania, which ranked in the order named, is 
grouped together to avoid revealing the operations of individual 


companies. 
171 


172 Blacks and Pitches 


Carbon Black produced from Natural Gas in the United States 
im 1922-23. 






















































































Value at plant, a ix 
State Producers| Number | Quantity honiene a yield per 
>. reporting. | of plants. (Ibs.) Averane nedid Ci Me. ft. 
Total, 8 (lbs.) 
(cents.) c. ft.). 

1922 | 
Louisiana ,,.., seneed : 14 18 41,966,856 | $3,564,393 8-5 38,004,000 1-1 
West Virginia ...... 11 18 20,095,481 | 1,714,576 85 12,087,000} 17 
Kentucky  ....cs00 3 3 4,306,875 416,549 9-7 2,300,000 1:9 
sas Kind ates ; : 

YOMING ,..,...00006 - . : 
Montana wa 1 1 1,425,917 124,100 87 1,238,000 1-2 
Pennsylvania ..,... 1 1 

vs a 26 43 67,795,129 | 5,819,618 8-6 53,629,000 1:3 
Louisiana ............ 29 35 101,398,881 | 8,415,566 8-3 82,974,000 1.2 
West Virginia ...... 11 20 20,038,415 | 1,983,385 9:9 13,722,000 1-5 
Kentucky  .......0. 6 6 10,058,887 758,091 7-5 5,906,000 1-7 
SE ORBS \ wactacasacnges 3 3 2,633,013 183,306 7-0 2,136,000 1:2 
fe era bases 2 : 

BhHoMa ...eaee 1 d ' 
Montana ... 1 1 4,133,452 351,718 8:5 4,358,000 0-9 
Pennsylvania ,..... | 1 1 

138,262,648 | 11,692,066 85 109,096,000 | 1:3 








: a In counting the total number of producers a producer operating in more than one State is counted 
only once. 


Summary of Statistics of Carbon Black from Natural Gas in 
the United States, 1919-1923. 















































1919. 1920. 1921. 
Number Of producers ....csscccoscccssssecvee 17 19 23 47 
Waumaber of Plants... .0rcocsrccseessenvesescecses 36 35 41 69 
Quantity produced : 
Louisiana ....cccccsccsssvesveececees LDS. | 14,024,606 | 18,565,498 | 31,003,615 | 41,966,856 | 101,398,881 
West Virginia ...cccssscceeesee 99 | 29,925,614 | 26,659,469 | 25,073,000 | 20,095,481 | 20,038,415 
Other Stshes ivcksssseselsaresschuss les 8,106,721 6,096,925 3,689,700 6,732,792 16,825,352 
Total ....ccccosssscsccecsesesssceee gp | 52,056,941 | 51,321,892 | 59,766,315 | 67,795,129 | 138,262,648 
Value at plants: 
TOGA « . sincesseidavnmescpivcanzes COREE 3,816,040 | 4,032,286 | 5,445,878 | 5,819,618 | 11,692,066 
Average per1b. .....cccccscreres CONES TB. 79 9-1 8-6 8-5 
Estimated quantity of natural gas used, 
srseecsseccevecneedd C. ft. | 49,896,000 | 40,599,000 | 50,565,000 | 53,629,000 | 109,096,000 
Average yield per Mc. ft.  csececossese LDS. 1-0 1:3 1-2 1:3 1:3 





APPENDIX II 


Messrs. SHELL-MEX LimiTEpD, London, through their Technical 
Department, have kindly supplied a detailed table showing the 
characteristics of their well-known grades of Mexphalte. This 
table should be studied in conjunction with Chapter XIV, on 
Petroleum Asphalts or Petroleum Residual Pitches: the manu- 
script was in the press when the table was furnished to the author, 
otherwise the information therein would have been incorporated in 
the text of Chapter XIV. 


Properties of Various Grades of Mexphalte. 





wide 3 9 ce px 5B es B. 5 ag 4 66 mR. 1 ” “é R, 7) o> 








Grade, Grade. Grade. Grade. Grade, Spramex. 

Specific gravity at 

BOOT iiss cedar sichins 1-035 1-036 1-041 1-039 1-038 1-028 
flash point—Cleve- 

~, -Opeti'Oap © icc... over 500°F | over 500°F | over 500°F over 500°F | 224°C=4385°F | 232°0=450°R 

Loss on heating, N.Y. 

oven, 5 hrs, at 

BA DT cnacecpunheners negligible negligible negligible negligible negligible 0:36% 
Sal pe ® ccavidsscresy ons 5-8% 55% 5:5% 489 4:8% $55% 
Asphaltenes ......s0000 261% 30:3% 37:8% 39-29% 36:5% 16:7% 
Soluble in OS, ......006 99:8% 99:8% 99-7% 99-5% 99-6% 99-8% 
Melting point 

Th, iI.) eaves neque 55°C =131°F | 68°O=154°F | 112°C =234°F | 135°O=275°F | 97°C =207°F | 39-5°C=104°F 
Melting point 
Sr Bs) ccstsaree eves 40°C =104°F | 53°C=127°F | 97°C=207°F | 120°C =248°F | 82°C=180°F | 24:5°C=76°R 

Conradson coking 

POR chwsctavcsdeomases 25-4% 26:0% 88-5% 26:5% 256% 19% 
Co-efficient of expan- 

sion per °C. approx. 0-0006 0-0006 0-0006 0-0006 0-0006 0-0006 
Penetration at 77°F 50 25 4 8 25 200 

- Ductility at 77°F ... 120+ 10 nil 1 4 120+ 

Dielectric strength 

PNM. LAD. veessenee +. 35,000 volts} + 35,000 volts} +-35,000 volts | +35,000 volts | +35,000 volts | +35,000 volts 
Ash (mineral) ......... 02% 02% 03% 0:2% 01% 02% 
Volatile matter (Con- 

radson values used) 746% 74% 61:5% 73-5% TA AY 81% 





173 


APPENDIX III 


THE statistics below have been kindly supplied to the author 
by the Department of Overseas Trade, London, 8.W. 1. 


Statement showing the imports, exports (domestic) and re-exports 
of the undermentioned articles into and from the United 
Kingdom during each of the years 1921, 1922 and 1923, and 
January to November 1924, so far as possible. 










IMPORTS. 1921. 1922. 1923. Jan. to Nov.: 1924. 










Total imports of : Cwts. &. Owts. £. Owts. £. Cwts. &. 
Oarbon blacks ...... 49,320 200,350 | 77,606 278,384 | 118,159 } 513,297 Not available. 
Pitch: Tons. Tons. Tons. Tons, 


‘wea? 
834 6,660 | 59,659 | 286,613] Not available. 
4,231 | 40,969| 4,493 | 34,367 

146,649 | 870,012 | 262,871 |1,464,321 | 256,076 | 1,827,995 


EXPORTS (produce and manufactures of the United Kingdom). 


Ooal-tar pitch......... 
Other sorts ......0.. 
Asphant and bitumen 


568 5,226 
5,746 | 114,391 
92,903 | 788,126 


Total exports of : Cwts. &. Owts. £. Owts. £ Owts. | &. 
Carbon blacks ...... 4,239 14,413 5,707 15,717 8,939 30,530 Not available. 
Pitch : Tons. Tons, Tons. Tons, &. 
Coal-tar pitch ...... 304,235 {1,805,794 | 424,691 |1,543,291 | 414,224 |2,527,016 | 276,493 | 1,218,462 
Other sorts  .......5. 1,190 24,978 4,154 45,566 13,130 | 100,869 Not available. 
Asphalt and bitumen Not separately distinguished, 
RE-EXPORTS (foreign and colonial merchandise). 
Total re-exports of : Owts. &. Owts. &. Owts. &. 
Carbon blacks ...... 775 4,792 1,201 5,081 6,807 34,346 Information 
Pitch : Tons. Tons. Tons. not available. 
Coal-tar pitch ...... 1 13 38 943 37 630 
Other sorts ......66. 297 8,463 306 7,364 242 4,413 
Asphalt and bitumen 4,850 52,570 3,578 30,908 7,194 47,820 





Note.—As from the 1st April, 1923, the term ‘‘ United Kingdom ”’ refers to Great Britain and Northern 
Ireland only. 


174 


INDEX OF NAMES 


ABRAHAM, H., 67, 68, 70, 71, 82, 83, 85— 
87, 98-100, 102, 103, 107, 108, 110, 
112, 119, 124, 125, 142, 143, 152 

Acheson, E. G., 17, 18 

Amer. Soc. Testing Materials, 83, 85, 87 

Anderton, B. A., 138 

Andés, L. E., 158 


Bardwell, 94 

Baskerville, 104 

Becher, 67 

Benson, H. K., 124 

Bernstein, F., 126 

Berthelot, 129 

Blood, A. R., 31, 33 

Blood, E. R., 31, 34 

Bone, W. A., 29, 30, 113, 114 

Bornstein, E., 126 

Brit. Eng. Standards Assocn., 52, 53, 67, 
159, 160, 166-170 

Brockedon, 19 

Brown, R. L., 78 

Brownlee, R. H., 37 

Burnice, H., 111 

Butler, T. H., 114, 121 

Byerley, F. X., 109 


Cabot, G. L., 27, 31, 33, 35, 40, 42, 44 
Cesalpinus, 19 
Calbeck, 49 

Campbell, A., 106, 107 
Carmody, P., 94, 95 
Cary-Curr, H. J., 89 
Chambers, 116 
Chevreul, 129 

Church, 8. R., 138 
Clark, 114 

Conté, 19, 21 

Craig, E. H. C., 92 


Damiens, A., 35 
Davey, W. P., 159 
Davis, L. L., 124 
Ditmar, 62 
Donath, E , 129 
Dow, D. B., 29 
Downs, C. R., 78 
Doyle, H. L., 18 
Drew, H. D. K., 17 
Dunstan, A. E., 83, 106, 107, 112, 155 
Dupré, F., 149 
Dupré, M., 148 


Ellis, C., 37 

Emtage, R. H., 100 , 
Engler, 85 

Errera, J., 140 

Evans, A. C., 44 
Evans, R. D., 64 


Fieldner, A. C., 38 © 
Fisher, H. C., 154 
Fleming, 163 


Gardner, H. A., 18, 25, 38, 49, 153, 158 


Geitel, 130 

Gesner, 109 

Géodrich, P., 140 
Graefe, E., 90, 111, 126 
Green, 48 

Greider, 61 

Griin, 80 

Gunning, 89 


Hammond, 116 
Hamor, 104 
Hepworth, T. C., 55 
Hershmann, 44 
Hird, 116 

Holde, D., 110 
Holdt, P., 158 
Horne, W. D., 23 
Horton, P. M., 23 
Howard, R. D., 78 
Hubbard, P., 138 
Hulme, W., 48 
Hutin, 111 


Icard, 8., 148 
Instit. of Petroleum Technologists, 83 
Irvine, R., 35, 57 


Johnson, 163 
Jones, 114 


Kawai, 8., 92 
Kewley, J., 106 
Kjeldahl, 89 
Klein, C. A., 48 
Kobayashi, 8., 92 
Kramer, G., 37 


Laird, W. G., 37 

Langton, H. M., 25, 38, 67, 70, 71, 99, 
109, 124, 130-133, 135, 137 

Lawrence, J. C., 123 

Lebeau, P., 35 

Lewes, V. B., 114, 115 

Lewis, M. H., 148 

Lewis, R. H., 138 

Lewkowitsch, J., 85, 130, 131 ~ 

Lomax, E. L., 112 

Lucas, A., 55 


Mabery, C. F., 99 

Maderna, 140 

Mansbridge, W., 87 

Marcusson, J., 89, 96, 109, 111, 121, 126, 
130 

Martin, G., 24 

May, P., 54 

Mayer, 18 

McCourt, C. O., 37 

McGuire, J. A., 37 

Mitchell, C. A., 19, 21, 55 

Morgan, G. T., 126 

Morrell, J. C., 38 

Morrell, R. 8., 149, 157, 159, 162, 163 


Neal, R. O., 14, 29, 31 


175 


176 


Nichols, 48 
Niepce, J. N., 140 
Nuttall, 47 


Pailler, E. C., 111 
Parrish, J., 48 

Pearson, A. R., 114 
Peckham, 8. F., 92 
Perrott, G. St. J., 40, 44 
Pickering, G. F., 90, 135 
Pritchard, T. W., 24 


Ralston, O. C., 82 

Ramsay, W., 92 

Redwood, Sir B., 85, 87, 106 

Reeve, C. 8., 138 

Remfry, F. G. P., 155 

Richardson, C., 67, 68, 89, 92, 93, 98, 
111, 165 

Richardson, G. B., 171, 172 

Rubencamp, 18 


Sarnow, C., 87 
Saybolt, 85 

Scharff, C. E., 126 
Scheele, 19 
Schippel, 63 
Schreiber, O., 144 
Schweizer, V., 125 
Sell, G., 105 

Selvig, W. A., 17, 38 
Serle, 67 

Sievers, E. G., 28 
Singleton, F., 154 
Sinkinson, E., 114 
Slater, W. E., 31 
Smith, J. Cruickshank, 13, 49, 51 
Smith, J. E., 44 
Smith, Watson, 104 


INDEX OF 


ACENAPHTHENES, 78 
Acetylene black, 35, 37 
Acetylenes, 76 
Acid-proof cements, 145, 146 
floors, 145, 146 
Acid-washed black, 23 
Ageing of bituminous materials, 139-140 
Agglomerated particles of blacks, 59 
Air-drying black enamels, 160-161 
Albertite, 103 
Alcohols, 79 
Aniline black, 157 
Animal charcoal, 23 
Anisotropic fillers in rubber, 64 
Anisotropy, 64 
Anthracenes, 78 
Archangel pitch, 123 
Asphalt, 66, 67, 69 
Bermudez, 93 
composition of, 75-82 
dampcoursing, 146-147 
definition of, 68, 70, 168 


Index of Names 


Soane, C. E., 80 

Spielmann, P. E., 67, 83, 139, 140 
Stanton, F. M., 38 

Stewart, E. G., 115 

Stockings, W. E., 114 

Stopes, M. C., 113 

Strasser, R., 129 

Sullivan, J. V., 56 

Svedberg, 48 

Szarvasy, E., 37 


Taylor, G. B., 17 
Thiessen, R., 40, 59 
Thole, F. B., 112, 115 
Tindale, H., 121, 166 
Toch, M., 138 


Uhlinger, R. H., 37 
Underwood, N., 56 


Vitruvius, 55 
Vogt, W. W., 64 


Ward, G. J., 146 
Warnes, A. R., 114, 116 
Weber, H. C. P., 163 
Weill, 8., 110 

Weiss, J. M., 78, 114, 138 
Wheeler, R. V., 113, 114 
Wiegand, 62, 63 
Wiegner, 48 

Wieland, W., 125 

Wijs, 90 

Wilkins, O., 23 

Wilton, 116 

Wright, 115, 166 
Wurtz, 129 


Zerr, 18 


SUBJECTS 


Asphalt, early history of, 66, 67 
in roadway construction, 164 
Judea, 140 
light sensitiveness of, 140 
Marcusson’s subdivision, 96 
native, occurrence of, 91-96 
origin of, 92-93 
paints, 151-155 - 
resins, 140 
roof felting, 143, 144 
Trinidad Lake, 92-95 
uses, 83 
waterproofing, 146-147 

Asphaltenes, 96, 121, 166 
in asphalt, 96 
in roadtars, 166 

Asphaltic cements, 166 
pyrobitumens, 69, 72, 103 

definition of, 71 

Asphaltites, 69, 72, 98-102 
definition of, 71 

Asphaltogenic acids, 96 


Index of Subjects 177 


Asphalt pavement, 164-165 
surface of, 165 
surface phenomena in, 165-166 
Asphalts, blown residual, 109, 110 
petroleum residual, 105, 108, 109 
sludge, 111 
sulphurised, 110, 111 
Asphaltum, 66 
Patagonian, 162 
Syrian, 162 


- Barytes, 62, 63 
Bitumen, 66, 67, 69 
composition of, 70, 75 
classes of, 72 
Dead Sea, 66 
definition of, 67, 70, 168 
Egyptian, 66 
occurrence in nature, 91 
Bituminous fabrics, 142 
cements, 145-146 
paints, 151 
paving materials, 164-168 
varnishes, 160-161 
Bituminous materials, 67 
ageing of, 139-140 
B.S. specification, 167, 168 
carbonisation of, 139 
chemical tests, 84, 88—90 
complete classification, 72, 73 
composition, 75-82 
effects of moisture on, 139 
for fabrics, 142 
for floorings, 144-145 
heat tests, 86, 87 
light sensitiveness of, 140 
physical tests, 84-86 
preliminary classification, 68 
solubility tests, 87, 88 
types of, 69 
weathering of, 138-140 
Blacklead, 16 
Black pigments, 13, 14 
classification of, 14 
fineness of, 48 
formation of, 14 
“long ” and “‘short,”’ 56, 60 
paint-making, 47 
properties of, 13 
properties of, in ink-making, 56, 57 
specific gravity, 47 
tinting strength, 49, 50 
uses of, 13 
uses of, in ink-making, 55-60 
Black stoving enamel, 157 
Blast-furnace tar, 72, 116, 119 
pitch, 72, 116, 119 
Boiled oil, 55 
Bone black, 22, 23 
Bone tar, 137 
pitch, 137, 153 
Brown coals, 126 
Brunswick blacks, 151, 157 


Cannel coals, 104, 126 
Carbon, 13 
‘short ” and “ long,” 59 


Carbon, as rubber pigment, 61, 62 
Carbon black, description of, 27 
analyses of, 38, 39, 45 
apparent surface of, 62 
bibliography, 40, 41 
B.S.S. in paint, 52, 53 
Channel process, 31, 32 
extent of industry, 28 
from coke-oven gas, 35 
in ink manufacture, 57-59, 60 
in paint manufacture, 47, 51 e 
methods of analysis, 38, 39 
methods of formation, 31 
plants in use and yields, 28 
Plate process, 33 
production in 1923, 171, 172 
properties of, 37 
rotating cylinder process, 34, 35 
rotating disc process, 33 
selling price of, 27 
theory of formation, 29, 30 
uses of, 40 
variation in yield of, 38 
various methods of manufacture, 35, 


37 
Carbon inks, 55 
Charcoal blacks, 14, 22 
Charcoals, analyses of, 25 
production, 14, 23, 24 
Chrysene, 57, 78 
Coal, 71 
action of solvents on, 114 
botanical origin of, 113 
brown, 126 
defined, 113 
occurrence of, 113 
various classes, 114 
Coal tar, 112 
characteristics of, 112 
classification of, 115 
composition, 114-115 
distillation of, 116-119 
production of, 112 
Coal-tar pitch, 112, 119, 167-169 
B.S. specification, 168-169 
characteristics of, 114, 119 
composition of, 114, 115 
for roofing purposes, 143 
for waterproofing, 147 
properties of, 121 
quantities of, 112 
Coke-oven gas, 35 
Coke-oven-tar, 115, 116 
Coke-oven-tar pitch, 115, 119 
Compound carbonaceous blacks, 15 
Compounding ingredients in rubber, 
61 


Cotton black grease, 129, 134 
Cotton-oil refining, 133, 134 
Cotton pitch, 129 
Cotton-seed fatty acids, 134 
mucilage, 134 
pitch, 129, 133-134 
Cotton pitch, 129, 133-134 
Cotton soap-stock, 134 
Cotton stearine pitch, 133-134 
Cracking, 14, 112, 136 


178 Index of Subjects 


Cyclo olefines, 77 
Cyclo paraffins, 76 


Damp-coursing, 146, 147 
Damp-proofing, 146, 147 
Deposited carbon blacks, 14 
Diolefines, 76 

Diphenyls, 77 

Dippel’s oil, 137 

Dispersed particles of blacks, 59 
Drop black, 23 


Elastic constants, 64 
Elaterite, 103 
Emulsification, 131 
Emulsions, bituminous, 165 


Fatty acid pitches, 129 
composition of, 136 
properties of, 137 

Fatty acids, 79, 129 
acetic series, 79 
distillation, 129-132 
oleic series, 80 

Fatty oils, constitution of, 129 
saponification, 129-131 

Fillers for paint, 152 
rubber, 61-64 

Fixed blacks, definition of, 13 
preparation of, 22-25 


Gilsonite, 98, 99, 100 
in enamels, 157 
in Japans, 156 
Glance pitch, 98, 100 
Grahamite, 98, 101, 102 
Graphite, analyses, 20 
analysis of, 17 
as a lubricant, 18 
in pencil manufacture, 19, 21 
manufacture, 17 
occurrence of, 16 
paint, 18 | 
pencil markings, 19, 21 
production of, 16 
properties, 16, 17 
uses of, 17, 18 


Hydrocarbons, 75 
acetylene, 76 
benzene, 77 
cyclic, 77, 78 
naphthenic, 76, 105 
olefine, 75 
paraffin, 75, 105 


Impregnating compounds, 149 

Impsonite, 103 

Indenes, 77, 78 

Indian ink, 55 

Insulating papers, 148 

Insulating varnishes, 162, 163 
chemical problems of, 163 
formula of, 163. 

Isotropic fillers in rubber, 64 

Ivory black, 23 


Japans, 155-159 

bituminous materials for, 156 

formule, 157 

pitting of, 158 

with water thinners, 159 
Jellying of asphalt paints, 154-155 
Judean asphalt, 140 


Ketones, 79 
Lampblack, 13, 42 


analyses, 45 
collection of, 43, 44 


contrasted with carbon black, 44, 45 
in ink-manufacture, 56, 57, 59, 60 


production, 42-44 
properties, 42 
quality of, 42 
yield, 42 
Lignite, 71 
tar, 126 
pitch, 126, 127, 153 


Magnetite, 15 
Manganese black, 15 
Manjak, 100 

Metallic blacks, 14, 15 
Mexphalte, 162, 173 
Mineral black, 25 
Monocyclic benzenes, 77 


Naphtha, coal-tar, 152 
petroleum, 107, 152 
wood, 152 

Naphthalenes, 77 

Naphthenes, 76 

Native asphalts, 72, 91, 168 

Natural gas, 27, 28, 31, 37 
composition, 30 

' testing, 29 

Nigrosines, 15 

Nitrogenous compounds, 81 

Non-asphaltic pyrobitumens, 69 
definition of, 71 


Oils for ink-making, 55 

Oil-gas pitch, 72, 127, 128 
tar, 72, 127, 128 

Olefine acetylenes, 76 

Olefines, 75 

Ozokerite, 70, 149 


Paint solvents, 152 

Paints, bituminous, 151 
graphite, 18 

Particle size, 48, 62 

Peat, 71, 125 
distillation products, 125, 126 
tar, 125 

Petrolenes, 26, 121, 166 

Petroleum, 70, 71 
comparison of derivatives, 98 
distillation schemes, 106, 107 
metamorphoses, 93 
origin of, 92, 136 
principal refinery products, 107 
products as solvents, 152 


Index of Subjects 179 


Petroleum, residual pitch, 105, 108, 109 Saponification, 129-131 


residuals, 108 Shales, 25, 71, 127 
world’s production, 106 Solvents, comparative volatilities, 
Phenols, 79 paint and varnish, 152 
Pigments, artists’, 54 Soot, 42 
Pigments, black, 47 Stearine pitches, 129 
bulking value, 49 composition, 136, 137 
colour of, 50 palm oil, 133 
fineness of, 48, 49 properties of, 129, 137 
in rubber mixtures, 61-64 uses in cables, 149 
oil absorption of, 49 floorings, 145 
_ pencil, 19, 21 paints, 151-155 
tinting strength of, 49, 50 varnishes, 137 
Pitch, 66, 67, 69, 167-169 whale oil, 133 
Archangel or pine, 123 yield of, 132 
blast-furnace tar, 72, 116, 119 Stress-strain relationships, 62, 63, 64 
bone-tar, 72, 137 Sugar-house black, 22 
B.S. specification, 168-169 Sulphur compounds, 80, 81 
coal-tar, 72, 112, 119 
coke-oven tar, 72, 115, 119 Tar, 67, 69, 166 
cotton, 72, 129, 133, 134 classification, 72, 73 
definition of, 71, 168 definition of, 71, 167 — 
fatty acid, 72, 129, 136, 137 distillation, 116-120 
oil-gas tar, 72, 127, 128 solvents, 152, 153 
peat tar, 72, 125 Tar macadam, 165 
_producer-gas tar, 116, 119 oil, 169, 170 
residual, 68 Thermal decomposition, 14 
rosin, 72, 124,125 Thinners, 151-153 
shale-tar, 72 Torbanites, 104 
stearine, 72, 129 Trinidad Lake asphalt, 92-95, 164, 165 
water-gas tar, 72, 127, 128 colloidal properties, 165 
wood-tar, 124, 153 Turpentine, 24, 152 
wool, 129 
Plumbago, 16 Varnish, 138, 151 
Poisson’s ratio, 64 air-drying, 162 
Polycyclic polymethylenes, 76 for inks, 55, 58-60 
Polymethylenes, 76 insulating, 162, 163 
Printing ink, 55 ~* lithographic, 58, 59 
main classes of work for, 55 Vegetable black, 44 
methods for practical test, 58, 59 charcoal, 24 
testing methods, 58 Vine black, 24 
tests on carbon black for, 57, 58 
Protection of metal surfaces, 153 Wax, montan, 70 
Pyrenes, 57, 78 _ native mineral, 71 
Pyrobitumens, 69, 91 paraffin, 70 
definition of, 70 Waterproofing, various, 146-148 
Pyrolusite, 15 Wood, charcoal, 22, 23 
Pyrolysis, 112, 136 yield of, 24 
Pyropissite, 104 classes of, 123 
Wood distillation, 24, 123 
Residual pitches, 68, 113, 167 solvents, 152 
Residuals in pyrogenous distillation, tar, 124 
113 pitch, 124, 153 
Resin acids, 80 oe Wool grease, ihe 
Resins, 152 este Feat tee 1 roe. 129. , 
Rosin, 149 Pei ae 4 Wurtzilite, 108, sey 8 $e Re 
oil, 149 ee Sue e oes “o> 
Rubber pigments, 61 se bgpecnaaa Weel grease, 135 
practical tests, 63 one caeat » 2929 


results for mixings, 63 > Sing oxide i peel tuber, 3%, 83 


TEP ree y 


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N.B 





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